diff --git a/RELEASE-NOTES-1.42 b/RELEASE-NOTES-1.42
index e33fd0d170a..5279bdb051b 100644
--- a/RELEASE-NOTES-1.42
+++ b/RELEASE-NOTES-1.42
@@ -438,6 +438,59 @@ because of Phabricator reports.
     - TransactionRoundDefiningUpdate
     - UserEditCountInfo
     - UserEditCountUpdate
+  - MediaWiki\HTMLForm:
+    - CodexHTMLForm
+    - CollapsibleFieldsetLayout
+    - HTMLForm
+    - HTMLFormActionFieldLayout
+    - HTMLFormElement
+    - HTMLFormField
+    - HTMLFormFieldLayout
+    - HTMLFormFieldRequiredOptionsException
+    - HTMLNestedFilterable
+    - OOUIHTMLForm
+    - VFormHTMLForm
+    - MediaWiki\HTMLForm\Field:
+      - HTMLApiField
+      - HTMLAutoCompleteSelectField
+      - HTMLButtonField
+      - HTMLCheckField
+      - HTMLCheckMatrix
+      - HTMLComboboxField
+      - HTMLDateTimeField
+      - HTMLEditTools
+      - HTMLExpiryField
+      - HTMLFileField
+      - HTMLFloatField
+      - HTMLFormFieldCloner
+      - HTMLFormFieldWithButton
+      - HTMLHiddenField
+      - HTMLInfoField
+      - HTMLIntField
+      - HTMLMultiSelectField
+      - HTMLNamespacesMultiselectField
+      - HTMLRadioField
+      - HTMLRestrictionsField
+      - HTMLSelectAndOtherField
+      - HTMLSelectField
+      - HTMLSelectLanguageField
+      - HTMLSelectLimitField
+      - HTMLSelectNamespace
+      - HTMLSelectNamespaceWithButton
+      - HTMLSelectOrOtherField
+      - HTMLSizeFilterField
+      - HTMLSubmitField
+      - HTMLTagFilter
+      - HTMLTagMultiselectField
+      - HTMLTextAreaField
+      - HTMLTextField
+      - HTMLTextFieldWithButton
+      - HTMLTimezoneField
+      - HTMLTitleTextField
+      - HTMLTitlesMultiselectField
+      - HTMLToggleSwitchField
+      - HTMLUserTextField
+      - HTMLUsersMultiselectField
   - MediaWiki\Installer:
     - DatabaseUpdater
     - MysqlUpdater
diff --git a/autoload.php b/autoload.php
index 8e552b4379f..5632cc185a1 100644
--- a/autoload.php
+++ b/autoload.php
@@ -1144,6 +1144,57 @@ $wgAutoloadLocalClasses = [
 	'MediaWiki\\FileBackend\\FSFile\\TempFSFileFactory' => __DIR__ . '/includes/libs/filebackend/fsfile/TempFSFileFactory.php',
 	'MediaWiki\\FileBackend\\LockManager\\LockManagerGroupFactory' => __DIR__ . '/includes/filebackend/lockmanager/LockManagerGroupFactory.php',
 	'MediaWiki\\FileRepo\\File\\FileSelectQueryBuilder' => __DIR__ . '/includes/filerepo/file/FileSelectQueryBuilder.php',
+	'MediaWiki\\HTMLForm\\CodexHTMLForm' => __DIR__ . '/includes/htmlform/CodexHTMLForm.php',
+	'MediaWiki\\HTMLForm\\CollapsibleFieldsetLayout' => __DIR__ . '/includes/htmlform/CollapsibleFieldsetLayout.php',
+	'MediaWiki\\HTMLForm\\Field\\HTMLApiField' => __DIR__ . '/includes/htmlform/fields/HTMLApiField.php',
+	'MediaWiki\\HTMLForm\\Field\\HTMLAutoCompleteSelectField' => __DIR__ . '/includes/htmlform/fields/HTMLAutoCompleteSelectField.php',
+	'MediaWiki\\HTMLForm\\Field\\HTMLButtonField' => __DIR__ . '/includes/htmlform/fields/HTMLButtonField.php',
+	'MediaWiki\\HTMLForm\\Field\\HTMLCheckField' => __DIR__ . '/includes/htmlform/fields/HTMLCheckField.php',
+	'MediaWiki\\HTMLForm\\Field\\HTMLCheckMatrix' => __DIR__ . '/includes/htmlform/fields/HTMLCheckMatrix.php',
+	'MediaWiki\\HTMLForm\\Field\\HTMLComboboxField' => __DIR__ . '/includes/htmlform/fields/HTMLComboboxField.php',
+	'MediaWiki\\HTMLForm\\Field\\HTMLDateTimeField' => __DIR__ . '/includes/htmlform/fields/HTMLDateTimeField.php',
+	'MediaWiki\\HTMLForm\\Field\\HTMLEditTools' => __DIR__ . '/includes/htmlform/fields/HTMLEditTools.php',
+	'MediaWiki\\HTMLForm\\Field\\HTMLExpiryField' => __DIR__ . '/includes/htmlform/fields/HTMLExpiryField.php',
+	'MediaWiki\\HTMLForm\\Field\\HTMLFileField' => __DIR__ . '/includes/htmlform/fields/HTMLFileField.php',
+	'MediaWiki\\HTMLForm\\Field\\HTMLFloatField' => __DIR__ . '/includes/htmlform/fields/HTMLFloatField.php',
+	'MediaWiki\\HTMLForm\\Field\\HTMLFormFieldCloner' => __DIR__ . '/includes/htmlform/fields/HTMLFormFieldCloner.php',
+	'MediaWiki\\HTMLForm\\Field\\HTMLFormFieldWithButton' => __DIR__ . '/includes/htmlform/fields/HTMLFormFieldWithButton.php',
+	'MediaWiki\\HTMLForm\\Field\\HTMLHiddenField' => __DIR__ . '/includes/htmlform/fields/HTMLHiddenField.php',
+	'MediaWiki\\HTMLForm\\Field\\HTMLInfoField' => __DIR__ . '/includes/htmlform/fields/HTMLInfoField.php',
+	'MediaWiki\\HTMLForm\\Field\\HTMLIntField' => __DIR__ . '/includes/htmlform/fields/HTMLIntField.php',
+	'MediaWiki\\HTMLForm\\Field\\HTMLMultiSelectField' => __DIR__ . '/includes/htmlform/fields/HTMLMultiSelectField.php',
+	'MediaWiki\\HTMLForm\\Field\\HTMLNamespacesMultiselectField' => __DIR__ . '/includes/htmlform/fields/HTMLNamespacesMultiselectField.php',
+	'MediaWiki\\HTMLForm\\Field\\HTMLRadioField' => __DIR__ . '/includes/htmlform/fields/HTMLRadioField.php',
+	'MediaWiki\\HTMLForm\\Field\\HTMLRestrictionsField' => __DIR__ . '/includes/htmlform/fields/HTMLRestrictionsField.php',
+	'MediaWiki\\HTMLForm\\Field\\HTMLSelectAndOtherField' => __DIR__ . '/includes/htmlform/fields/HTMLSelectAndOtherField.php',
+	'MediaWiki\\HTMLForm\\Field\\HTMLSelectField' => __DIR__ . '/includes/htmlform/fields/HTMLSelectField.php',
+	'MediaWiki\\HTMLForm\\Field\\HTMLSelectLanguageField' => __DIR__ . '/includes/htmlform/fields/HTMLSelectLanguageField.php',
+	'MediaWiki\\HTMLForm\\Field\\HTMLSelectLimitField' => __DIR__ . '/includes/htmlform/fields/HTMLSelectLimitField.php',
+	'MediaWiki\\HTMLForm\\Field\\HTMLSelectNamespace' => __DIR__ . '/includes/htmlform/fields/HTMLSelectNamespace.php',
+	'MediaWiki\\HTMLForm\\Field\\HTMLSelectNamespaceWithButton' => __DIR__ . '/includes/htmlform/fields/HTMLSelectNamespaceWithButton.php',
+	'MediaWiki\\HTMLForm\\Field\\HTMLSelectOrOtherField' => __DIR__ . '/includes/htmlform/fields/HTMLSelectOrOtherField.php',
+	'MediaWiki\\HTMLForm\\Field\\HTMLSizeFilterField' => __DIR__ . '/includes/htmlform/fields/HTMLSizeFilterField.php',
+	'MediaWiki\\HTMLForm\\Field\\HTMLSubmitField' => __DIR__ . '/includes/htmlform/fields/HTMLSubmitField.php',
+	'MediaWiki\\HTMLForm\\Field\\HTMLTagFilter' => __DIR__ . '/includes/htmlform/fields/HTMLTagFilter.php',
+	'MediaWiki\\HTMLForm\\Field\\HTMLTagMultiselectField' => __DIR__ . '/includes/htmlform/fields/HTMLTagMultiselectField.php',
+	'MediaWiki\\HTMLForm\\Field\\HTMLTextAreaField' => __DIR__ . '/includes/htmlform/fields/HTMLTextAreaField.php',
+	'MediaWiki\\HTMLForm\\Field\\HTMLTextField' => __DIR__ . '/includes/htmlform/fields/HTMLTextField.php',
+	'MediaWiki\\HTMLForm\\Field\\HTMLTextFieldWithButton' => __DIR__ . '/includes/htmlform/fields/HTMLTextFieldWithButton.php',
+	'MediaWiki\\HTMLForm\\Field\\HTMLTimezoneField' => __DIR__ . '/includes/htmlform/fields/HTMLTimezoneField.php',
+	'MediaWiki\\HTMLForm\\Field\\HTMLTitleTextField' => __DIR__ . '/includes/htmlform/fields/HTMLTitleTextField.php',
+	'MediaWiki\\HTMLForm\\Field\\HTMLTitlesMultiselectField' => __DIR__ . '/includes/htmlform/fields/HTMLTitlesMultiselectField.php',
+	'MediaWiki\\HTMLForm\\Field\\HTMLToggleSwitchField' => __DIR__ . '/includes/htmlform/fields/HTMLToggleSwitchField.php',
+	'MediaWiki\\HTMLForm\\Field\\HTMLUserTextField' => __DIR__ . '/includes/htmlform/fields/HTMLUserTextField.php',
+	'MediaWiki\\HTMLForm\\Field\\HTMLUsersMultiselectField' => __DIR__ . '/includes/htmlform/fields/HTMLUsersMultiselectField.php',
+	'MediaWiki\\HTMLForm\\HTMLForm' => __DIR__ . '/includes/htmlform/HTMLForm.php',
+	'MediaWiki\\HTMLForm\\HTMLFormActionFieldLayout' => __DIR__ . '/includes/htmlform/HTMLFormActionFieldLayout.php',
+	'MediaWiki\\HTMLForm\\HTMLFormElement' => __DIR__ . '/includes/htmlform/HTMLFormElement.php',
+	'MediaWiki\\HTMLForm\\HTMLFormField' => __DIR__ . '/includes/htmlform/HTMLFormField.php',
+	'MediaWiki\\HTMLForm\\HTMLFormFieldLayout' => __DIR__ . '/includes/htmlform/HTMLFormFieldLayout.php',
+	'MediaWiki\\HTMLForm\\HTMLFormFieldRequiredOptionsException' => __DIR__ . '/includes/htmlform/HTMLFormFieldRequiredOptionsException.php',
+	'MediaWiki\\HTMLForm\\HTMLNestedFilterable' => __DIR__ . '/includes/htmlform/HTMLNestedFilterable.php',
+	'MediaWiki\\HTMLForm\\OOUIHTMLForm' => __DIR__ . '/includes/htmlform/OOUIHTMLForm.php',
+	'MediaWiki\\HTMLForm\\VFormHTMLForm' => __DIR__ . '/includes/htmlform/VFormHTMLForm.php',
 	'MediaWiki\\HeaderCallback' => __DIR__ . '/includes/Request/HeaderCallback.php',
 	'MediaWiki\\HookContainer\\DeprecatedHooks' => __DIR__ . '/includes/HookContainer/DeprecatedHooks.php',
 	'MediaWiki\\HookContainer\\FauxGlobalHookArray' => __DIR__ . '/includes/HookContainer/FauxGlobalHookArray.php',
diff --git a/includes/actions/Hook/ActionBeforeFormDisplayHook.php b/includes/actions/Hook/ActionBeforeFormDisplayHook.php
index d6785d57b20..f13ec9cb6f6 100644
--- a/includes/actions/Hook/ActionBeforeFormDisplayHook.php
+++ b/includes/actions/Hook/ActionBeforeFormDisplayHook.php
@@ -3,7 +3,7 @@
 namespace MediaWiki\Hook;
 
 use Article;
-use HTMLForm;
+use MediaWiki\HTMLForm\HTMLForm;
 
 /**
  * This is a hook handler interface, see docs/Hooks.md.
diff --git a/includes/htmlform/CodexHTMLForm.php b/includes/htmlform/CodexHTMLForm.php
index 0964e60c63c..6a47d80cbbf 100644
--- a/includes/htmlform/CodexHTMLForm.php
+++ b/includes/htmlform/CodexHTMLForm.php
@@ -21,6 +21,8 @@
  * @file
  */
 
+namespace MediaWiki\HTMLForm;
+
 use MediaWiki\Html\Html;
 
 /**
@@ -66,3 +68,6 @@ class CodexHTMLForm extends HTMLForm {
 		return Html::rawElement( 'form', $this->getFormAttributes(), $html );
 	}
 }
+
+/** @deprecated since 1.42 */
+class_alias( CodexHTMLForm::class, 'CodexHTMLForm' );
diff --git a/includes/htmlform/CollapsibleFieldsetLayout.php b/includes/htmlform/CollapsibleFieldsetLayout.php
index 99c04a2a9f8..628f7d32d33 100644
--- a/includes/htmlform/CollapsibleFieldsetLayout.php
+++ b/includes/htmlform/CollapsibleFieldsetLayout.php
@@ -1,9 +1,11 @@
 <?php
 
+namespace MediaWiki\HTMLForm;
+
 /*
  * @stable to extend
  */
-class CollapsibleFieldsetLayout extends OOUI\FieldsetLayout {
+class CollapsibleFieldsetLayout extends \OOUI\FieldsetLayout {
 	/**
 	 * @stable to call
 	 * @inheritDoc
@@ -19,11 +21,11 @@ class CollapsibleFieldsetLayout extends OOUI\FieldsetLayout {
 		$this->group->addClasses( [ 'mw-collapsible-content' ] );
 
 		$this->header->appendContent(
-			new OOUI\IconWidget( [
+			new \OOUI\IconWidget( [
 				'icon' => 'expand',
 				'label' => wfMessage( 'collapsible-expand' )->text(),
 			] ),
-			new OOUI\IconWidget( [
+			new \OOUI\IconWidget( [
 				'icon' => 'collapse',
 				'label' => wfMessage( 'collapsible-collapse' )->text(),
 			] )
@@ -34,3 +36,6 @@ class CollapsibleFieldsetLayout extends OOUI\FieldsetLayout {
 		] );
 	}
 }
+
+/** @deprecated since 1.42 */
+class_alias( CollapsibleFieldsetLayout::class, 'CollapsibleFieldsetLayout' );
diff --git a/includes/htmlform/HTMLForm.php b/includes/htmlform/HTMLForm.php
index aaf213ccdf1..f67ecd65a2a 100644
--- a/includes/htmlform/HTMLForm.php
+++ b/includes/htmlform/HTMLForm.php
@@ -21,10 +21,51 @@
  * @file
  */
 
+namespace MediaWiki\HTMLForm;
+
+use DomainException;
+use InvalidArgumentException;
+use LogicException;
 use MediaWiki\Context\ContextSource;
 use MediaWiki\Context\IContextSource;
 use MediaWiki\HookContainer\ProtectedHookAccessorTrait;
 use MediaWiki\Html\Html;
+use MediaWiki\HTMLForm\Field\HTMLApiField;
+use MediaWiki\HTMLForm\Field\HTMLAutoCompleteSelectField;
+use MediaWiki\HTMLForm\Field\HTMLCheckField;
+use MediaWiki\HTMLForm\Field\HTMLCheckMatrix;
+use MediaWiki\HTMLForm\Field\HTMLComboboxField;
+use MediaWiki\HTMLForm\Field\HTMLDateTimeField;
+use MediaWiki\HTMLForm\Field\HTMLEditTools;
+use MediaWiki\HTMLForm\Field\HTMLExpiryField;
+use MediaWiki\HTMLForm\Field\HTMLFileField;
+use MediaWiki\HTMLForm\Field\HTMLFloatField;
+use MediaWiki\HTMLForm\Field\HTMLFormFieldCloner;
+use MediaWiki\HTMLForm\Field\HTMLHiddenField;
+use MediaWiki\HTMLForm\Field\HTMLInfoField;
+use MediaWiki\HTMLForm\Field\HTMLIntField;
+use MediaWiki\HTMLForm\Field\HTMLMultiSelectField;
+use MediaWiki\HTMLForm\Field\HTMLNamespacesMultiselectField;
+use MediaWiki\HTMLForm\Field\HTMLRadioField;
+use MediaWiki\HTMLForm\Field\HTMLSelectAndOtherField;
+use MediaWiki\HTMLForm\Field\HTMLSelectField;
+use MediaWiki\HTMLForm\Field\HTMLSelectLanguageField;
+use MediaWiki\HTMLForm\Field\HTMLSelectLimitField;
+use MediaWiki\HTMLForm\Field\HTMLSelectNamespace;
+use MediaWiki\HTMLForm\Field\HTMLSelectNamespaceWithButton;
+use MediaWiki\HTMLForm\Field\HTMLSelectOrOtherField;
+use MediaWiki\HTMLForm\Field\HTMLSizeFilterField;
+use MediaWiki\HTMLForm\Field\HTMLSubmitField;
+use MediaWiki\HTMLForm\Field\HTMLTagFilter;
+use MediaWiki\HTMLForm\Field\HTMLTagMultiselectField;
+use MediaWiki\HTMLForm\Field\HTMLTextAreaField;
+use MediaWiki\HTMLForm\Field\HTMLTextField;
+use MediaWiki\HTMLForm\Field\HTMLTextFieldWithButton;
+use MediaWiki\HTMLForm\Field\HTMLTimezoneField;
+use MediaWiki\HTMLForm\Field\HTMLTitlesMultiselectField;
+use MediaWiki\HTMLForm\Field\HTMLTitleTextField;
+use MediaWiki\HTMLForm\Field\HTMLUsersMultiselectField;
+use MediaWiki\HTMLForm\Field\HTMLUserTextField;
 use MediaWiki\Linker\Linker;
 use MediaWiki\Linker\LinkTarget;
 use MediaWiki\MainConfigNames;
@@ -33,6 +74,11 @@ use MediaWiki\Parser\Sanitizer;
 use MediaWiki\Status\Status;
 use MediaWiki\Title\Title;
 use MediaWiki\Title\TitleValue;
+use Message;
+use MessageSpecifier;
+use StatusValue;
+use Stringable;
+use Xml;
 
 /**
  * Object handling generic submission, CSRF protection, layout and
@@ -1362,7 +1408,7 @@ class HTMLForm extends ContextSource {
 	 *
 	 * @stable to override
 	 * @param string $html HTML contents to wrap.
-	 * @return string|OOUI\Tag Wrapped HTML.
+	 * @return string|\OOUI\Tag Wrapped HTML.
 	 */
 	public function wrapForm( $html ) {
 		# Include a <fieldset> wrapper for style, if requested.
@@ -2220,3 +2266,6 @@ class HTMLForm extends ContextSource {
 		return false;
 	}
 }
+
+/** @deprecated since 1.42 */
+class_alias( HTMLForm::class, 'HTMLForm' );
diff --git a/includes/htmlform/HTMLFormActionFieldLayout.php b/includes/htmlform/HTMLFormActionFieldLayout.php
index edaaaf301c0..2f753ca4166 100644
--- a/includes/htmlform/HTMLFormActionFieldLayout.php
+++ b/includes/htmlform/HTMLFormActionFieldLayout.php
@@ -1,9 +1,11 @@
 <?php
 
+namespace MediaWiki\HTMLForm;
+
 /*
  * @stable to extend
  */
-class HTMLFormActionFieldLayout extends OOUI\ActionFieldLayout {
+class HTMLFormActionFieldLayout extends \OOUI\ActionFieldLayout {
 	use HTMLFormElement;
 
 	/**
@@ -21,3 +23,6 @@ class HTMLFormActionFieldLayout extends OOUI\ActionFieldLayout {
 		return 'mw.htmlform.ActionFieldLayout';
 	}
 }
+
+/** @deprecated since 1.42 */
+class_alias( HTMLFormActionFieldLayout::class, 'HTMLFormActionFieldLayout' );
diff --git a/includes/htmlform/HTMLFormElement.php b/includes/htmlform/HTMLFormElement.php
index 366fdf6b4bb..8ca19589d7f 100644
--- a/includes/htmlform/HTMLFormElement.php
+++ b/includes/htmlform/HTMLFormElement.php
@@ -1,5 +1,7 @@
 <?php
 
+namespace MediaWiki\HTMLForm;
+
 /**
  * Allows custom data specific to HTMLFormField to be set for OOUI forms. A matching JS widget
  * (defined in htmlform.Element.js) picks up the extra config when constructed using OO.ui.infuse().
@@ -33,3 +35,6 @@ trait HTMLFormElement {
 		} );
 	}
 }
+
+/** @deprecated since 1.42 */
+class_alias( HTMLFormElement::class, 'HTMLFormElement' );
diff --git a/includes/htmlform/HTMLFormField.php b/includes/htmlform/HTMLFormField.php
index adbd7dd220b..ca083a763df 100644
--- a/includes/htmlform/HTMLFormField.php
+++ b/includes/htmlform/HTMLFormField.php
@@ -1,10 +1,20 @@
 <?php
 
+namespace MediaWiki\HTMLForm;
+
+use FormatJson;
+use HtmlArmor;
+use HTMLCheckField;
+use HTMLFormFieldCloner;
+use InvalidArgumentException;
 use MediaWiki\Context\RequestContext;
 use MediaWiki\Html\Html;
 use MediaWiki\Linker\Linker;
 use MediaWiki\Request\WebRequest;
 use MediaWiki\Status\Status;
+use Message;
+use MessageSpecifier;
+use StatusValue;
 
 /**
  * The parent class to generate form fields.  Any field type should
@@ -69,7 +79,7 @@ abstract class HTMLFormField {
 	 * @stable to override
 	 *
 	 * @param string $value
-	 * @return OOUI\Widget|string|false
+	 * @return \OOUI\Widget|string|false
 	 */
 	public function getInputOOUI( $value ) {
 		return false;
@@ -700,7 +710,7 @@ abstract class HTMLFormField {
 	 *
 	 * @param string $value The value to set the input to.
 	 *
-	 * @return OOUI\FieldLayout
+	 * @return \OOUI\FieldLayout
 	 */
 	public function getOOUI( $value ) {
 		$inputField = $this->getInputOOUI( $value );
@@ -710,7 +720,7 @@ abstract class HTMLFormField {
 			// generate the whole field, label and errors and all, then wrap it in a Widget.
 			// It might look weird, but it'll work OK.
 			return $this->getFieldLayoutOOUI(
-				new OOUI\Widget( [ 'content' => new OOUI\HtmlSnippet( $this->getDiv( $value ) ) ] ),
+				new \OOUI\Widget( [ 'content' => new \OOUI\HtmlSnippet( $this->getDiv( $value ) ) ] ),
 				[ 'align' => 'top' ]
 			);
 		}
@@ -720,7 +730,7 @@ abstract class HTMLFormField {
 			// We have an OOUI implementation, but it's not proper, and we got a load of HTML.
 			// Cheat a little and wrap it in a widget. It won't be infusable, though, since client-side
 			// JavaScript doesn't know how to rebuilt the contents.
-			$inputField = new OOUI\Widget( [ 'content' => new OOUI\HtmlSnippet( $inputField ) ] );
+			$inputField = new \OOUI\Widget( [ 'content' => new \OOUI\HtmlSnippet( $inputField ) ] );
 			$infusable = false;
 		}
 
@@ -728,13 +738,13 @@ abstract class HTMLFormField {
 		$help = $this->getHelpText();
 		$errors = $this->getErrorsRaw( $value );
 		foreach ( $errors as &$error ) {
-			$error = new OOUI\HtmlSnippet( $error );
+			$error = new \OOUI\HtmlSnippet( $error );
 		}
 
 		$config = [
 			'classes' => [ "mw-htmlform-field-$fieldType" ],
 			'align' => $this->getLabelAlignOOUI(),
-			'help' => ( $help !== null && $help !== '' ) ? new OOUI\HtmlSnippet( $help ) : null,
+			'help' => ( $help !== null && $help !== '' ) ? new \OOUI\HtmlSnippet( $help ) : null,
 			'errors' => $errors,
 			'infusable' => $infusable,
 			'helpInline' => $this->isHelpInline(),
@@ -757,7 +767,7 @@ abstract class HTMLFormField {
 		// the element could specify, that the label doesn't need to be added
 		$label = $this->getLabel();
 		if ( $label && $label !== "\u{00A0}" && $label !== '&#160;' ) {
-			$config['label'] = new OOUI\HtmlSnippet( $label );
+			$config['label'] = new \OOUI\HtmlSnippet( $label );
 		}
 
 		if ( $this->mCondState ) {
@@ -798,9 +808,9 @@ abstract class HTMLFormField {
 
 	/**
 	 * Get a FieldLayout (or subclass thereof) to wrap this field in when using OOUI output.
-	 * @param OOUI\Widget $inputField
+	 * @param \OOUI\Widget $inputField
 	 * @param array $config
-	 * @return OOUI\FieldLayout
+	 * @return \OOUI\FieldLayout
 	 */
 	protected function getFieldLayoutOOUI( $inputField, $config ) {
 		return new HTMLFormFieldLayout( $inputField, $config );
@@ -1312,3 +1322,6 @@ abstract class HTMLFormField {
 		return (bool)$this->mCondState;
 	}
 }
+
+/** @deprecated since 1.42 */
+class_alias( HTMLFormField::class, 'HTMLFormField' );
diff --git a/includes/htmlform/HTMLFormFieldLayout.php b/includes/htmlform/HTMLFormFieldLayout.php
index cba2f0fe272..a0d0ed9223e 100644
--- a/includes/htmlform/HTMLFormFieldLayout.php
+++ b/includes/htmlform/HTMLFormFieldLayout.php
@@ -1,10 +1,12 @@
 <?php
 
+namespace MediaWiki\HTMLForm;
+
 /*
  * @stable to extend
  */
-class HTMLFormFieldLayout extends OOUI\FieldLayout {
-	use HTMLFormElement;
+class HTMLFormFieldLayout extends \OOUI\FieldLayout {
+	use \MediaWiki\HTMLForm\HTMLFormElement;
 
 	/**
 	 * @stable to call
@@ -21,3 +23,6 @@ class HTMLFormFieldLayout extends OOUI\FieldLayout {
 		return 'mw.htmlform.FieldLayout';
 	}
 }
+
+/** @deprecated since 1.42 */
+class_alias( HTMLFormFieldLayout::class, 'HTMLFormFieldLayout' );
diff --git a/includes/htmlform/HTMLFormFieldRequiredOptionsException.php b/includes/htmlform/HTMLFormFieldRequiredOptionsException.php
index 056e5ecb02b..8aaa9ad283b 100644
--- a/includes/htmlform/HTMLFormFieldRequiredOptionsException.php
+++ b/includes/htmlform/HTMLFormFieldRequiredOptionsException.php
@@ -1,5 +1,9 @@
 <?php
 
+namespace MediaWiki\HTMLForm;
+
+use InvalidArgumentException;
+
 /**
  * @newable
  * @stable to extend
@@ -18,3 +22,6 @@ class HTMLFormFieldRequiredOptionsException extends InvalidArgumentException {
 			implode( ', ', $missing ) ) );
 	}
 }
+
+/** @deprecated since 1.42 */
+class_alias( HTMLFormFieldRequiredOptionsException::class, 'HTMLFormFieldRequiredOptionsException' );
diff --git a/includes/htmlform/HTMLNestedFilterable.php b/includes/htmlform/HTMLNestedFilterable.php
index a68ab62dadb..73305563641 100644
--- a/includes/htmlform/HTMLNestedFilterable.php
+++ b/includes/htmlform/HTMLNestedFilterable.php
@@ -1,5 +1,7 @@
 <?php
 
+namespace MediaWiki\HTMLForm;
+
 interface HTMLNestedFilterable {
 	/**
 	 * Support for separating multi-option preferences into multiple preferences
@@ -9,3 +11,6 @@ interface HTMLNestedFilterable {
 	 */
 	public function filterDataForSubmit( $data );
 }
+
+/** @deprecated since 1.42 */
+class_alias( HTMLNestedFilterable::class, 'HTMLNestedFilterable' );
diff --git a/includes/htmlform/OOUIHTMLForm.php b/includes/htmlform/OOUIHTMLForm.php
index c73863c1657..f9aa90466a2 100644
--- a/includes/htmlform/OOUIHTMLForm.php
+++ b/includes/htmlform/OOUIHTMLForm.php
@@ -1,5 +1,7 @@
 <?php
 
+namespace MediaWiki\HTMLForm;
+
 /**
  * HTML form generation and submission handling, OOUI style.
  *
@@ -21,6 +23,7 @@
  * @file
  */
 
+use DomainException;
 use MediaWiki\Html\Html;
 use MediaWiki\Linker\Linker;
 use MediaWiki\Parser\Sanitizer;
@@ -83,18 +86,18 @@ class OOUIHTMLForm extends HTMLForm {
 				];
 			}
 
-			$buttons .= new OOUI\ButtonInputWidget( $attribs );
+			$buttons .= new \OOUI\ButtonInputWidget( $attribs );
 		}
 
 		if ( $this->mShowReset ) {
-			$buttons .= new OOUI\ButtonInputWidget( [
+			$buttons .= new \OOUI\ButtonInputWidget( [
 				'type' => 'reset',
 				'label' => $this->msg( 'htmlform-reset' )->text(),
 			] );
 		}
 
 		if ( $this->mShowCancel ) {
-			$buttons .= new OOUI\ButtonWidget( [
+			$buttons .= new \OOUI\ButtonWidget( [
 				'label' => $this->msg( 'cancel' )->text(),
 				'href' => $this->getCancelTargetURL(),
 			] );
@@ -114,18 +117,18 @@ class OOUIHTMLForm extends HTMLForm {
 			}
 
 			if ( isset( $button['label-message'] ) ) {
-				$label = new OOUI\HtmlSnippet( $this->getMessage( $button['label-message'] )->parse() );
+				$label = new \OOUI\HtmlSnippet( $this->getMessage( $button['label-message'] )->parse() );
 			} elseif ( isset( $button['label'] ) ) {
 				$label = $button['label'];
 			} elseif ( isset( $button['label-raw'] ) ) {
-				$label = new OOUI\HtmlSnippet( $button['label-raw'] );
+				$label = new \OOUI\HtmlSnippet( $button['label-raw'] );
 			} else {
 				$label = $button['value'];
 			}
 
 			$attrs['classes'] = isset( $attrs['class'] ) ? (array)$attrs['class'] : [];
 
-			$buttons .= new OOUI\ButtonInputWidget( [
+			$buttons .= new \OOUI\ButtonInputWidget( [
 				'type' => 'submit',
 				'name' => $button['name'],
 				'value' => $button['value'],
@@ -147,22 +150,22 @@ class OOUIHTMLForm extends HTMLForm {
 
 	/**
 	 * @inheritDoc
-	 * @return OOUI\PanelLayout
+	 * @return \OOUI\PanelLayout
 	 */
 	protected function wrapFieldSetSection( $legend, $section, $attributes, $isRoot ) {
 		// to get a user visible effect, wrap the fieldset into a framed panel layout
-		$layout = new OOUI\PanelLayout( [
+		$layout = new \OOUI\PanelLayout( [
 			'expanded' => false,
 			'padded' => true,
 			'framed' => true,
 		] );
 
 		$layout->appendContent(
-			new OOUI\FieldsetLayout( [
+			new \OOUI\FieldsetLayout( [
 				'label' => $legend,
 				'items' => [
-					new OOUI\Widget( [
-						'content' => new OOUI\HtmlSnippet( $section )
+					new \OOUI\Widget( [
+						'content' => new \OOUI\HtmlSnippet( $section )
 					] ),
 				],
 			] + $attributes )
@@ -172,7 +175,7 @@ class OOUIHTMLForm extends HTMLForm {
 
 	/**
 	 * @inheritDoc
-	 * @return OOUI\FieldLayout HTML
+	 * @return \OOUI\FieldLayout HTML
 	 */
 	protected function formatField( HTMLFormField $field, $value ) {
 		return $field->getOOUI( $value );
@@ -180,7 +183,7 @@ class OOUIHTMLForm extends HTMLForm {
 
 	/**
 	 * Put a form section together from the individual fields' HTML, merging it and wrapping.
-	 * @param OOUI\FieldLayout[] $fieldsHtml Array of outputs from formatField()
+	 * @param \OOUI\FieldLayout[] $fieldsHtml Array of outputs from formatField()
 	 * @param string $sectionName
 	 * @param bool $anyFieldHasLabel Unused
 	 * @return string HTML
@@ -236,7 +239,7 @@ class OOUIHTMLForm extends HTMLForm {
 		}
 
 		foreach ( $errors as &$error ) {
-			$error = new OOUI\HtmlSnippet( $error );
+			$error = new \OOUI\HtmlSnippet( $error );
 		}
 
 		// Used in formatFormHeader()
@@ -268,11 +271,11 @@ class OOUIHTMLForm extends HTMLForm {
 		];
 		// if there's no header, don't create an (empty) LabelWidget, simply use a placeholder
 		if ( $this->mHeader ) {
-			$element = new OOUI\LabelWidget( [ 'label' => new OOUI\HtmlSnippet( $this->mHeader ) ] );
+			$element = new \OOUI\LabelWidget( [ 'label' => new \OOUI\HtmlSnippet( $this->mHeader ) ] );
 		} else {
-			$element = new OOUI\Widget( [] );
+			$element = new \OOUI\Widget( [] );
 		}
-		return new OOUI\FieldLayout(
+		return new \OOUI\FieldLayout(
 			$element,
 			[
 				'align' => 'top',
@@ -289,27 +292,27 @@ class OOUIHTMLForm extends HTMLForm {
 
 	public function wrapForm( $html ) {
 		if ( is_string( $this->mWrapperLegend ) ) {
-			$phpClass = $this->mCollapsible ? CollapsibleFieldsetLayout::class : OOUI\FieldsetLayout::class;
+			$phpClass = $this->mCollapsible ? CollapsibleFieldsetLayout::class : \OOUI\FieldsetLayout::class;
 			$content = new $phpClass( [
 				'label' => $this->mWrapperLegend,
 				'collapsed' => $this->mCollapsed,
 				'items' => [
-					new OOUI\Widget( [
-						'content' => new OOUI\HtmlSnippet( $html )
+					new \OOUI\Widget( [
+						'content' => new \OOUI\HtmlSnippet( $html )
 					] ),
 				],
-			] + OOUI\Element::configFromHtmlAttributes( $this->mWrapperAttributes ) );
+			] + \OOUI\Element::configFromHtmlAttributes( $this->mWrapperAttributes ) );
 		} else {
-			$content = new OOUI\HtmlSnippet( $html );
+			$content = new \OOUI\HtmlSnippet( $html );
 		}
 
-		$form = new OOUI\FormLayout( $this->getFormAttributes() + [
+		$form = new \OOUI\FormLayout( $this->getFormAttributes() + [
 			'classes' => [ 'mw-htmlform', 'mw-htmlform-ooui' ],
 			'content' => $content,
 		] );
 
 		// Include a wrapper for style, if requested.
-		$form = new OOUI\PanelLayout( [
+		$form = new \OOUI\PanelLayout( [
 			'classes' => [ 'mw-htmlform-ooui-wrapper' ],
 			'expanded' => false,
 			'padded' => $this->mWrapperLegend !== false,
@@ -320,3 +323,6 @@ class OOUIHTMLForm extends HTMLForm {
 		return $form;
 	}
 }
+
+/** @deprecated since 1.42 */
+class_alias( OOUIHTMLForm::class, 'OOUIHTMLForm' );
diff --git a/includes/htmlform/VFormHTMLForm.php b/includes/htmlform/VFormHTMLForm.php
index 10a71f8195e..9a2b434dc36 100644
--- a/includes/htmlform/VFormHTMLForm.php
+++ b/includes/htmlform/VFormHTMLForm.php
@@ -1,5 +1,7 @@
 <?php
 
+namespace MediaWiki\HTMLForm;
+
 /**
  * HTML form generation and submission handling, vertical-form style.
  *
@@ -73,3 +75,6 @@ class VFormHTMLForm extends HTMLForm {
 		return Html::rawElement( 'form', $this->getFormAttributes(), $html );
 	}
 }
+
+/** @deprecated since 1.42 */
+class_alias( VFormHTMLForm::class, 'VFormHTMLForm' );
diff --git a/includes/htmlform/fields/HTMLApiField.php b/includes/htmlform/fields/HTMLApiField.php
index 658a2bfb8de..119a1ffacc6 100644
--- a/includes/htmlform/fields/HTMLApiField.php
+++ b/includes/htmlform/fields/HTMLApiField.php
@@ -1,5 +1,9 @@
 <?php
 
+namespace MediaWiki\HTMLForm\Field;
+
+use MediaWiki\HTMLForm\HTMLFormField;
+
 /**
  * @stable to extend
  */
@@ -24,3 +28,6 @@ class HTMLApiField extends HTMLFormField {
 		return false;
 	}
 }
+
+/** @deprecated since 1.42 */
+class_alias( HTMLApiField::class, 'HTMLApiField' );
diff --git a/includes/htmlform/fields/HTMLAutoCompleteSelectField.php b/includes/htmlform/fields/HTMLAutoCompleteSelectField.php
index 8b7d5055e99..c82dc3347ba 100644
--- a/includes/htmlform/fields/HTMLAutoCompleteSelectField.php
+++ b/includes/htmlform/fields/HTMLAutoCompleteSelectField.php
@@ -1,5 +1,12 @@
 <?php
 
+namespace MediaWiki\HTMLForm\Field;
+
+use FormatJson;
+use InvalidArgumentException;
+use MediaWiki\HTMLForm\HTMLFormField;
+use XmlSelect;
+
 /**
  * Text field for selecting a value from a large list of possible values, with
  * auto-completion and optionally with a select dropdown for selecting common
@@ -182,3 +189,6 @@ class HTMLAutoCompleteSelectField extends HTMLTextField {
 		return false;
 	}
 }
+
+/** @deprecated since 1.42 */
+class_alias( HTMLAutoCompleteSelectField::class, 'HTMLAutoCompleteSelectField' );
diff --git a/includes/htmlform/fields/HTMLButtonField.php b/includes/htmlform/fields/HTMLButtonField.php
index 678dec75482..b3c75b4a5f7 100644
--- a/includes/htmlform/fields/HTMLButtonField.php
+++ b/includes/htmlform/fields/HTMLButtonField.php
@@ -1,7 +1,13 @@
 <?php
 
+namespace MediaWiki\HTMLForm\Field;
+
 use MediaWiki\Context\RequestContext;
 use MediaWiki\Html\Html;
+use MediaWiki\HTMLForm\CodexHTMLForm;
+use MediaWiki\HTMLForm\HTMLFormField;
+use MediaWiki\HTMLForm\VFormHTMLForm;
+use Message;
 
 /**
  * Adds a generic button inline to the form. Does not do anything, you must add
@@ -100,21 +106,21 @@ class HTMLButtonField extends HTMLFormField {
 	 * Get the OOUI widget for this field.
 	 * @stable to override
 	 * @param string $value
-	 * @return OOUI\ButtonInputWidget
+	 * @return \OOUI\ButtonInputWidget
 	 */
 	public function getInputOOUI( $value ) {
-		return new OOUI\ButtonInputWidget( [
+		return new \OOUI\ButtonInputWidget( [
 			'name' => $this->mName,
 			'value' => $this->getDefault(),
 			'label' => !$this->isBadIE() && $this->buttonLabel
-				? new OOUI\HtmlSnippet( $this->buttonLabel )
+				? new \OOUI\HtmlSnippet( $this->buttonLabel )
 				: $this->getDefault(),
 			'type' => $this->buttonType,
 			'classes' => [ 'mw-htmlform-submit', $this->mClass ],
 			'id' => $this->mID,
 			'flags' => $this->mFlags,
 			'useInputTag' => $this->isBadIE(),
-		] + OOUI\Element::configFromHtmlAttributes(
+		] + \OOUI\Element::configFromHtmlAttributes(
 			$this->getAttributes( [ 'disabled', 'tabindex' ] )
 		) );
 	}
@@ -151,3 +157,6 @@ class HTMLButtonField extends HTMLFormField {
 		return (bool)preg_match( '/MSIE [1-7]\./i', $request->getHeader( 'User-Agent' ) );
 	}
 }
+
+/** @deprecated since 1.42 */
+class_alias( HTMLButtonField::class, 'HTMLButtonField' );
diff --git a/includes/htmlform/fields/HTMLCheckField.php b/includes/htmlform/fields/HTMLCheckField.php
index 673aea7f7de..53e84ec713f 100644
--- a/includes/htmlform/fields/HTMLCheckField.php
+++ b/includes/htmlform/fields/HTMLCheckField.php
@@ -1,7 +1,15 @@
 <?php
 
+namespace MediaWiki\HTMLForm\Field;
+
 use MediaWiki\Html\Html;
+use MediaWiki\HTMLForm\CodexHTMLForm;
+use MediaWiki\HTMLForm\HTMLForm;
+use MediaWiki\HTMLForm\HTMLFormField;
+use MediaWiki\HTMLForm\OOUIHTMLForm;
+use MediaWiki\HTMLForm\VFormHTMLForm;
 use MediaWiki\Request\WebRequest;
+use Xml;
 
 /**
  * A checkbox field
@@ -66,7 +74,7 @@ class HTMLCheckField extends HTMLFormField {
 	 * @stable to override
 	 * @since 1.26
 	 * @param string $value
-	 * @return OOUI\CheckboxInputWidget The checkbox widget.
+	 * @return \OOUI\CheckboxInputWidget The checkbox widget.
 	 */
 	public function getInputOOUI( $value ) {
 		if ( !empty( $this->mParams['invert'] ) ) {
@@ -77,7 +85,7 @@ class HTMLCheckField extends HTMLFormField {
 		$attr['id'] = $this->mID;
 		$attr['name'] = $this->mName;
 
-		$attr += OOUI\Element::configFromHtmlAttributes(
+		$attr += \OOUI\Element::configFromHtmlAttributes(
 			$this->getAttributes( [ 'disabled', 'tabindex' ] )
 		);
 
@@ -88,7 +96,7 @@ class HTMLCheckField extends HTMLFormField {
 		$attr['selected'] = $value;
 		$attr['value'] = '1'; // Nasty hack, but needed to make this work
 
-		return new OOUI\CheckboxInputWidget( $attr );
+		return new \OOUI\CheckboxInputWidget( $attr );
 	}
 
 	/**
@@ -160,3 +168,6 @@ class HTMLCheckField extends HTMLFormField {
 		}
 	}
 }
+
+/** @deprecated since 1.42 */
+class_alias( HTMLCheckField::class, 'HTMLCheckField' );
diff --git a/includes/htmlform/fields/HTMLCheckMatrix.php b/includes/htmlform/fields/HTMLCheckMatrix.php
index 80238138b81..7e8d509d9b3 100644
--- a/includes/htmlform/fields/HTMLCheckMatrix.php
+++ b/includes/htmlform/fields/HTMLCheckMatrix.php
@@ -1,7 +1,14 @@
 <?php
 
+namespace MediaWiki\HTMLForm\Field;
+
+use FormatJson;
 use MediaWiki\Html\Html;
+use MediaWiki\HTMLForm\HTMLFormField;
+use MediaWiki\HTMLForm\HTMLFormFieldRequiredOptionsException;
+use MediaWiki\HTMLForm\HTMLNestedFilterable;
 use MediaWiki\Request\WebRequest;
+use Xml;
 
 /**
  * A checkbox matrix
@@ -166,7 +173,7 @@ class HTMLCheckMatrix extends HTMLFormField implements HTMLNestedFilterable {
 	public function getInputOOUI( $value ) {
 		$attribs = $this->getAttributes( [ 'disabled', 'tabindex' ] );
 
-		return new MediaWiki\Widget\CheckMatrixWidget(
+		return new \MediaWiki\Widget\CheckMatrixWidget(
 			[
 				'name' => $this->mName,
 				'infusable' => true,
@@ -178,7 +185,7 @@ class HTMLCheckMatrix extends HTMLFormField implements HTMLNestedFilterable {
 				'forcedOff' => $this->mParams['force-options-off'] ?? [],
 				'forcedOn' => $this->mParams['force-options-on'] ?? [],
 				'values' => $value,
-			] + OOUI\Element::configFromHtmlAttributes( $attribs )
+			] + \OOUI\Element::configFromHtmlAttributes( $attribs )
 		);
 	}
 
@@ -289,3 +296,6 @@ class HTMLCheckMatrix extends HTMLFormField implements HTMLNestedFilterable {
 		return true;
 	}
 }
+
+/** @deprecated since 1.42 */
+class_alias( HTMLCheckMatrix::class, 'HTMLCheckMatrix' );
diff --git a/includes/htmlform/fields/HTMLComboboxField.php b/includes/htmlform/fields/HTMLComboboxField.php
index 1ff9355c1e3..9b8a9db4ad5 100644
--- a/includes/htmlform/fields/HTMLComboboxField.php
+++ b/includes/htmlform/fields/HTMLComboboxField.php
@@ -1,5 +1,9 @@
 <?php
 
+namespace MediaWiki\HTMLForm\Field;
+
+use XmlSelect;
+
 /**
  * A combo box field.
  *
@@ -38,7 +42,7 @@ class HTMLComboboxField extends HTMLTextField {
 	public function getInputOOUI( $value ) {
 		$disabled = false;
 		$allowedParams = [ 'tabindex' ];
-		$attribs = OOUI\Element::configFromHtmlAttributes(
+		$attribs = \OOUI\Element::configFromHtmlAttributes(
 			$this->getAttributes( $allowedParams )
 		);
 
@@ -54,7 +58,7 @@ class HTMLComboboxField extends HTMLTextField {
 			$attribs['placeholder'] = $this->mPlaceholder;
 		}
 
-		return new OOUI\ComboBoxInputWidget( [
+		return new \OOUI\ComboBoxInputWidget( [
 			'name' => $this->mName,
 			'id' => $this->mID,
 			'options' => $this->getOptionsOOUI(),
@@ -67,3 +71,6 @@ class HTMLComboboxField extends HTMLTextField {
 		return true;
 	}
 }
+
+/** @deprecated since 1.42 */
+class_alias( HTMLComboboxField::class, 'HTMLComboboxField' );
diff --git a/includes/htmlform/fields/HTMLDateTimeField.php b/includes/htmlform/fields/HTMLDateTimeField.php
index 50ae32f1b90..40cc2d15678 100644
--- a/includes/htmlform/fields/HTMLDateTimeField.php
+++ b/includes/htmlform/fields/HTMLDateTimeField.php
@@ -1,5 +1,11 @@
 <?php
 
+namespace MediaWiki\HTMLForm\Field;
+
+use DateTime;
+use DateTimeZone;
+use Exception;
+use InvalidArgumentException;
 use Wikimedia\RequestTimeout\TimeoutException;
 
 /**
@@ -165,15 +171,15 @@ class HTMLDateTimeField extends HTMLTextField {
 			'id' => $this->mID,
 		];
 
-		$params += OOUI\Element::configFromHtmlAttributes(
+		$params += \OOUI\Element::configFromHtmlAttributes(
 			$this->getAttributes( [ 'disabled', 'readonly', 'min', 'max' ] )
 		);
 
 		if ( $this->mType === 'date' ) {
 			$this->mParent->getOutput()->addModuleStyles( 'mediawiki.widgets.DateInputWidget.styles' );
-			return new MediaWiki\Widget\DateInputWidget( $params );
+			return new \MediaWiki\Widget\DateInputWidget( $params );
 		} else {
-			return new MediaWiki\Widget\DateTimeInputWidget( $params );
+			return new \MediaWiki\Widget\DateTimeInputWidget( $params );
 		}
 	}
 
@@ -190,3 +196,6 @@ class HTMLDateTimeField extends HTMLTextField {
 	}
 
 }
+
+/** @deprecated since 1.42 */
+class_alias( HTMLDateTimeField::class, 'HTMLDateTimeField' );
diff --git a/includes/htmlform/fields/HTMLEditTools.php b/includes/htmlform/fields/HTMLEditTools.php
index 3805e5811a3..45f422c24d2 100644
--- a/includes/htmlform/fields/HTMLEditTools.php
+++ b/includes/htmlform/fields/HTMLEditTools.php
@@ -1,5 +1,9 @@
 <?php
 
+namespace MediaWiki\HTMLForm\Field;
+
+use MediaWiki\HTMLForm\HTMLFormField;
+
 /*
  * @stable to extend
  */
@@ -51,3 +55,6 @@ class HTMLEditTools extends HTMLFormField {
 		return $msg;
 	}
 }
+
+/** @deprecated since 1.42 */
+class_alias( HTMLEditTools::class, 'HTMLEditTools' );
diff --git a/includes/htmlform/fields/HTMLExpiryField.php b/includes/htmlform/fields/HTMLExpiryField.php
index f9f29e7501d..0e0c65ca0cd 100644
--- a/includes/htmlform/fields/HTMLExpiryField.php
+++ b/includes/htmlform/fields/HTMLExpiryField.php
@@ -1,5 +1,9 @@
 <?php
 
+namespace MediaWiki\HTMLForm\Field;
+
+use MediaWiki\HTMLForm\HTMLForm;
+use MediaWiki\HTMLForm\HTMLFormField;
 use MediaWiki\Widget\ExpiryInputWidget;
 
 /**
@@ -91,3 +95,6 @@ class HTMLExpiryField extends HTMLFormField {
 	}
 
 }
+
+/** @deprecated since 1.42 */
+class_alias( HTMLExpiryField::class, 'HTMLExpiryField' );
diff --git a/includes/htmlform/fields/HTMLFileField.php b/includes/htmlform/fields/HTMLFileField.php
index d3e0caf4d23..3a13793311b 100644
--- a/includes/htmlform/fields/HTMLFileField.php
+++ b/includes/htmlform/fields/HTMLFileField.php
@@ -1,6 +1,9 @@
 <?php
 
+namespace MediaWiki\HTMLForm\Field;
+
 use MediaWiki\Html\Html;
+use MediaWiki\HTMLForm\HTMLFormField;
 use OOUI\Widget;
 
 /**
@@ -121,7 +124,7 @@ class HTMLFileField extends HTMLFormField {
 			'readonly',
 		];
 
-		$attribs += OOUI\Element::configFromHtmlAttributes(
+		$attribs += \OOUI\Element::configFromHtmlAttributes(
 			$this->getAttributes( $allowedParams )
 		);
 
@@ -140,7 +143,7 @@ class HTMLFileField extends HTMLFormField {
 	 * @return Widget
 	 */
 	protected function getInputWidget( $params ) {
-		return new OOUI\SelectFileInputWidget( $params );
+		return new \OOUI\SelectFileInputWidget( $params );
 	}
 
 	/**
@@ -151,3 +154,6 @@ class HTMLFileField extends HTMLFormField {
 		return true;
 	}
 }
+
+/** @deprecated since 1.42 */
+class_alias( HTMLFileField::class, 'HTMLFileField' );
diff --git a/includes/htmlform/fields/HTMLFloatField.php b/includes/htmlform/fields/HTMLFloatField.php
index 0a20afc5e9f..9f4d6f4e41b 100644
--- a/includes/htmlform/fields/HTMLFloatField.php
+++ b/includes/htmlform/fields/HTMLFloatField.php
@@ -1,5 +1,7 @@
 <?php
 
+namespace MediaWiki\HTMLForm\Field;
+
 /**
  * A field that will contain a numeric value
  *
@@ -51,6 +53,9 @@ class HTMLFloatField extends HTMLTextField {
 	 * @stable to override
 	 */
 	protected function getInputWidget( $params ) {
-		return new OOUI\NumberInputWidget( $params );
+		return new \OOUI\NumberInputWidget( $params );
 	}
 }
+
+/** @deprecated since 1.42 */
+class_alias( HTMLFloatField::class, 'HTMLFloatField' );
diff --git a/includes/htmlform/fields/HTMLFormFieldCloner.php b/includes/htmlform/fields/HTMLFormFieldCloner.php
index 27205eb44f2..6c6fa1ed104 100644
--- a/includes/htmlform/fields/HTMLFormFieldCloner.php
+++ b/includes/htmlform/fields/HTMLFormFieldCloner.php
@@ -1,8 +1,14 @@
 <?php
 
+namespace MediaWiki\HTMLForm\Field;
+
+use InvalidArgumentException;
 use MediaWiki\Html\Html;
+use MediaWiki\HTMLForm\HTMLForm;
+use MediaWiki\HTMLForm\HTMLFormField;
 use MediaWiki\Parser\Sanitizer;
 use MediaWiki\Request\DerivativeRequest;
+use Xml;
 
 /**
  * A container for HTMLFormFields that allows for multiple copies of the set of
@@ -573,3 +579,6 @@ class HTMLFormFieldCloner extends HTMLFormField {
 		return $html;
 	}
 }
+
+/** @deprecated since 1.42 */
+class_alias( HTMLFormFieldCloner::class, 'HTMLFormFieldCloner' );
diff --git a/includes/htmlform/fields/HTMLFormFieldWithButton.php b/includes/htmlform/fields/HTMLFormFieldWithButton.php
index 9f155f23e1c..dc6c586da84 100644
--- a/includes/htmlform/fields/HTMLFormFieldWithButton.php
+++ b/includes/htmlform/fields/HTMLFormFieldWithButton.php
@@ -1,6 +1,9 @@
 <?php
 
+namespace MediaWiki\HTMLForm\Field;
+
 use MediaWiki\Html\Html;
+use MediaWiki\HTMLForm\HTMLFormField;
 
 /**
  * Enables HTMLFormField elements to be build with a button.
@@ -64,14 +67,14 @@ class HTMLFormFieldWithButton extends HTMLFormField {
 	}
 
 	public function getInputOOUI( $value ) {
-		return new OOUI\ButtonInputWidget( [
+		return new \OOUI\ButtonInputWidget( [
 			'name' => $this->mButtonName,
 			'value' => $this->mButtonValue,
 			'type' => $this->mButtonType,
 			'label' => $this->mButtonValue,
 			'flags' => $this->mButtonFlags,
 			'id' => $this->mButtonId ?: null,
-		] + OOUI\Element::configFromHtmlAttributes(
+		] + \OOUI\Element::configFromHtmlAttributes(
 			$this->getAttributes( [ 'disabled', 'tabindex' ] )
 		) );
 	}
@@ -85,3 +88,6 @@ class HTMLFormFieldWithButton extends HTMLFormField {
 		return $element . "\u{00A0}" . $this->getInputHTML( '' );
 	}
 }
+
+/** @deprecated since 1.42 */
+class_alias( HTMLFormFieldWithButton::class, 'HTMLFormFieldWithButton' );
diff --git a/includes/htmlform/fields/HTMLHiddenField.php b/includes/htmlform/fields/HTMLHiddenField.php
index a594662b2f7..d52184b67da 100644
--- a/includes/htmlform/fields/HTMLHiddenField.php
+++ b/includes/htmlform/fields/HTMLHiddenField.php
@@ -1,5 +1,9 @@
 <?php
 
+namespace MediaWiki\HTMLForm\Field;
+
+use MediaWiki\HTMLForm\HTMLFormField;
+
 /*
  * @stable to extend
  */
@@ -71,3 +75,6 @@ class HTMLHiddenField extends HTMLFormField {
 		return false;
 	}
 }
+
+/** @deprecated since 1.42 */
+class_alias( HTMLHiddenField::class, 'HTMLHiddenField' );
diff --git a/includes/htmlform/fields/HTMLInfoField.php b/includes/htmlform/fields/HTMLInfoField.php
index 39f0e7d8830..f820657b9cd 100644
--- a/includes/htmlform/fields/HTMLInfoField.php
+++ b/includes/htmlform/fields/HTMLInfoField.php
@@ -1,5 +1,10 @@
 <?php
 
+namespace MediaWiki\HTMLForm\Field;
+
+use Closure;
+use MediaWiki\HTMLForm\HTMLFormField;
+
 /**
  * An information field (text blob), not a proper input.
  * @stable to extend
@@ -48,10 +53,10 @@ class HTMLInfoField extends HTMLFormField {
 	 */
 	public function getInputOOUI( $value ) {
 		if ( !empty( $this->mParams['raw'] ) ) {
-			$value = new OOUI\HtmlSnippet( $value );
+			$value = new \OOUI\HtmlSnippet( $value );
 		}
 
-		return new OOUI\LabelWidget( [
+		return new \OOUI\LabelWidget( [
 			'label' => $value,
 			'id' => $this->mID
 		] );
@@ -100,12 +105,12 @@ class HTMLInfoField extends HTMLFormField {
 	/**
 	 * @stable to override
 	 * @param mixed $value If not FieldLayout or subclass has been deprecated.
-	 * @return OOUI\FieldLayout
+	 * @return \OOUI\FieldLayout
 	 * @since 1.32
 	 */
 	public function getOOUI( $value ) {
 		if ( !empty( $this->mParams['rawrow'] ) ) {
-			if ( !( $value instanceof OOUI\FieldLayout ) ) {
+			if ( !( $value instanceof \OOUI\FieldLayout ) ) {
 				wfDeprecatedMsg( __METHOD__ . ": 'default' parameter as a string when using " .
 					"'rawrow' was deprecated in MediaWiki 1.32 (must be a FieldLayout or subclass)",
 					'1.32' );
@@ -124,3 +129,6 @@ class HTMLInfoField extends HTMLFormField {
 		return false;
 	}
 }
+
+/** @deprecated since 1.42 */
+class_alias( HTMLInfoField::class, 'HTMLInfoField' );
diff --git a/includes/htmlform/fields/HTMLIntField.php b/includes/htmlform/fields/HTMLIntField.php
index c504d2602d7..7b78154c811 100644
--- a/includes/htmlform/fields/HTMLIntField.php
+++ b/includes/htmlform/fields/HTMLIntField.php
@@ -1,5 +1,7 @@
 <?php
 
+namespace MediaWiki\HTMLForm\Field;
+
 /**
  * A field that must contain a number
  *
@@ -31,3 +33,6 @@ class HTMLIntField extends HTMLFloatField {
 		return true;
 	}
 }
+
+/** @deprecated since 1.42 */
+class_alias( HTMLIntField::class, 'HTMLIntField' );
diff --git a/includes/htmlform/fields/HTMLMultiSelectField.php b/includes/htmlform/fields/HTMLMultiSelectField.php
index 7590a17c6ef..c8eaf1ea2a4 100644
--- a/includes/htmlform/fields/HTMLMultiSelectField.php
+++ b/includes/htmlform/fields/HTMLMultiSelectField.php
@@ -1,7 +1,14 @@
 <?php
 
+namespace MediaWiki\HTMLForm\Field;
+
 use MediaWiki\Html\Html;
+use MediaWiki\HTMLForm\HTMLFormField;
+use MediaWiki\HTMLForm\HTMLNestedFilterable;
+use MediaWiki\HTMLForm\OOUIHTMLForm;
 use MediaWiki\Request\WebRequest;
+use RuntimeException;
+use Xml;
 
 /**
  * Multi-select field
@@ -167,7 +174,7 @@ class HTMLMultiSelectField extends HTMLFormField implements HTMLNestedFilterable
 	 * @stable to override
 	 * @since 1.28
 	 * @param string[] $value
-	 * @return string|OOUI\CheckboxMultiselectInputWidget
+	 * @return string|\OOUI\CheckboxMultiselectInputWidget
 	 * @suppress PhanParamSignatureMismatch
 	 */
 	public function getInputOOUI( $value ) {
@@ -217,7 +224,7 @@ class HTMLMultiSelectField extends HTMLFormField implements HTMLNestedFilterable
 			unset( $option );
 			$attr['options'] = $options;
 
-			$attr += OOUI\Element::configFromHtmlAttributes(
+			$attr += \OOUI\Element::configFromHtmlAttributes(
 				$this->getAttributes( [ 'disabled', 'tabindex' ] )
 			);
 
@@ -225,12 +232,12 @@ class HTMLMultiSelectField extends HTMLFormField implements HTMLNestedFilterable
 				$attr['classes'] = [ $this->mClass ];
 			}
 
-			$widget = new OOUI\CheckboxMultiselectInputWidget( $attr );
+			$widget = new \OOUI\CheckboxMultiselectInputWidget( $attr );
 			if ( $sectionLabel ) {
-				$out[] = new OOUI\FieldsetLayout( [
+				$out[] = new \OOUI\FieldsetLayout( [
 					'items' => [ $widget ],
 					// @phan-suppress-next-line SecurityCheck-XSS Key is html, taint cannot track that
-					'label' => new OOUI\HtmlSnippet( $sectionLabel ),
+					'label' => new \OOUI\HtmlSnippet( $sectionLabel ),
 				] );
 			} else {
 				$out[] = $widget;
@@ -306,3 +313,6 @@ class HTMLMultiSelectField extends HTMLFormField implements HTMLNestedFilterable
 		return false;
 	}
 }
+
+/** @deprecated since 1.42 */
+class_alias( HTMLMultiSelectField::class, 'HTMLMultiSelectField' );
diff --git a/includes/htmlform/fields/HTMLNamespacesMultiselectField.php b/includes/htmlform/fields/HTMLNamespacesMultiselectField.php
index 8820db59ab8..c448f2d6634 100644
--- a/includes/htmlform/fields/HTMLNamespacesMultiselectField.php
+++ b/includes/htmlform/fields/HTMLNamespacesMultiselectField.php
@@ -1,5 +1,7 @@
 <?php
 
+namespace MediaWiki\HTMLForm\Field;
+
 use MediaWiki\MediaWikiServices;
 use MediaWiki\Widget\NamespacesMultiselectWidget;
 
@@ -121,3 +123,6 @@ class HTMLNamespacesMultiselectField extends HTMLSelectNamespace {
 	}
 
 }
+
+/** @deprecated since 1.42 */
+class_alias( HTMLNamespacesMultiselectField::class, 'HTMLNamespacesMultiselectField' );
diff --git a/includes/htmlform/fields/HTMLRadioField.php b/includes/htmlform/fields/HTMLRadioField.php
index 7688fd06d81..15747b2a659 100644
--- a/includes/htmlform/fields/HTMLRadioField.php
+++ b/includes/htmlform/fields/HTMLRadioField.php
@@ -1,7 +1,11 @@
 <?php
 
+namespace MediaWiki\HTMLForm\Field;
+
 use MediaWiki\Html\Html;
+use MediaWiki\HTMLForm\HTMLFormField;
 use MediaWiki\Parser\Sanitizer;
+use Xml;
 
 /**
  * Radio checkbox fields.
@@ -68,16 +72,16 @@ class HTMLRadioField extends HTMLFormField {
 			$options[] = [
 				'data' => $data,
 				// @phan-suppress-next-line SecurityCheck-XSS Labels are raw when not from message
-				'label' => $this->mOptionsLabelsNotFromMessage ? new OOUI\HtmlSnippet( $label ) : $label,
+				'label' => $this->mOptionsLabelsNotFromMessage ? new \OOUI\HtmlSnippet( $label ) : $label,
 			];
 		}
 
-		return new OOUI\RadioSelectInputWidget( [
+		return new \OOUI\RadioSelectInputWidget( [
 			'name' => $this->mName,
 			'id' => $this->mID,
 			'value' => $value,
 			'options' => $options,
-		] + OOUI\Element::configFromHtmlAttributes(
+		] + \OOUI\Element::configFromHtmlAttributes(
 			$this->getAttributes( [ 'disabled', 'tabindex' ] )
 		) );
 	}
@@ -114,3 +118,6 @@ class HTMLRadioField extends HTMLFormField {
 		return false;
 	}
 }
+
+/** @deprecated since 1.42 */
+class_alias( HTMLRadioField::class, 'HTMLRadioField' );
diff --git a/includes/htmlform/fields/HTMLRestrictionsField.php b/includes/htmlform/fields/HTMLRestrictionsField.php
index b81754fd208..e1b7e74e4f0 100644
--- a/includes/htmlform/fields/HTMLRestrictionsField.php
+++ b/includes/htmlform/fields/HTMLRestrictionsField.php
@@ -1,7 +1,12 @@
 <?php
 
+namespace MediaWiki\HTMLForm\Field;
+
+use MediaWiki\HTMLForm\HTMLFormField;
 use MediaWiki\MediaWikiServices;
 use MediaWiki\Request\WebRequest;
+use Message;
+use MWRestrictions;
 
 /**
  * Class for updating an MWRestrictions value (which is, currently, basically just an IP address
@@ -131,3 +136,6 @@ class HTMLRestrictionsField extends HTMLFormField {
 		);
 	}
 }
+
+/** @deprecated since 1.42 */
+class_alias( HTMLRestrictionsField::class, 'HTMLRestrictionsField' );
diff --git a/includes/htmlform/fields/HTMLSelectAndOtherField.php b/includes/htmlform/fields/HTMLSelectAndOtherField.php
index fb86fd78847..1faef4dff64 100644
--- a/includes/htmlform/fields/HTMLSelectAndOtherField.php
+++ b/includes/htmlform/fields/HTMLSelectAndOtherField.php
@@ -1,7 +1,11 @@
 <?php
 
+namespace MediaWiki\HTMLForm\Field;
+
+use InvalidArgumentException;
 use MediaWiki\Html\Html;
 use MediaWiki\Request\WebRequest;
+use MediaWiki\Widget\SelectWithInputWidget;
 
 /**
  * Double field with a dropdown list constructed from a system message in the format
@@ -106,7 +110,7 @@ class HTMLSelectAndOtherField extends HTMLSelectField {
 			'maxlength',
 		];
 
-		$textAttribs += OOUI\Element::configFromHtmlAttributes(
+		$textAttribs += \OOUI\Element::configFromHtmlAttributes(
 			$this->getAttributes( $allowedParams )
 		);
 
@@ -122,7 +126,7 @@ class HTMLSelectAndOtherField extends HTMLSelectField {
 			'disabled',
 		];
 
-		$dropdownInputAttribs += OOUI\Element::configFromHtmlAttributes(
+		$dropdownInputAttribs += \OOUI\Element::configFromHtmlAttributes(
 			$this->getAttributes( $allowedParams )
 		);
 
@@ -155,7 +159,7 @@ class HTMLSelectAndOtherField extends HTMLSelectField {
 	 * @return \MediaWiki\Widget\SelectWithInputWidget
 	 */
 	public function getInputWidget( $params ) {
-		return new MediaWiki\Widget\SelectWithInputWidget( $params );
+		return new SelectWithInputWidget( $params );
 	}
 
 	/**
@@ -238,3 +242,6 @@ class HTMLSelectAndOtherField extends HTMLSelectField {
 		return true;
 	}
 }
+
+/** @deprecated since 1.42 */
+class_alias( HTMLSelectAndOtherField::class, 'HTMLSelectAndOtherField' );
diff --git a/includes/htmlform/fields/HTMLSelectField.php b/includes/htmlform/fields/HTMLSelectField.php
index 86d027298fc..923cbc45edd 100644
--- a/includes/htmlform/fields/HTMLSelectField.php
+++ b/includes/htmlform/fields/HTMLSelectField.php
@@ -1,5 +1,10 @@
 <?php
 
+namespace MediaWiki\HTMLForm\Field;
+
+use MediaWiki\HTMLForm\HTMLFormField;
+use XmlSelect;
+
 /**
  * A select dropdown field.  Basically a wrapper for Xmlselect class
  *
@@ -60,7 +65,7 @@ class HTMLSelectField extends HTMLFormField {
 	public function getInputOOUI( $value ) {
 		$disabled = false;
 		$allowedParams = [ 'tabindex' ];
-		$attribs = OOUI\Element::configFromHtmlAttributes(
+		$attribs = \OOUI\Element::configFromHtmlAttributes(
 			$this->getAttributes( $allowedParams )
 		);
 
@@ -72,7 +77,7 @@ class HTMLSelectField extends HTMLFormField {
 			$disabled = true;
 		}
 
-		return new OOUI\DropdownInputWidget( [
+		return new \OOUI\DropdownInputWidget( [
 			'name' => $this->mName,
 			'id' => $this->mID,
 			'options' => $this->getOptionsOOUI(),
@@ -89,3 +94,6 @@ class HTMLSelectField extends HTMLFormField {
 		return true;
 	}
 }
+
+/** @deprecated since 1.42 */
+class_alias( HTMLSelectField::class, 'HTMLSelectField' );
diff --git a/includes/htmlform/fields/HTMLSelectLanguageField.php b/includes/htmlform/fields/HTMLSelectLanguageField.php
index 8a737e958ec..1dcdc95505c 100644
--- a/includes/htmlform/fields/HTMLSelectLanguageField.php
+++ b/includes/htmlform/fields/HTMLSelectLanguageField.php
@@ -1,5 +1,8 @@
 <?php
 
+namespace MediaWiki\HTMLForm\Field;
+
+use MediaWiki\HTMLForm\HTMLForm;
 use MediaWiki\MainConfigNames;
 use MediaWiki\MediaWikiServices;
 
@@ -44,3 +47,6 @@ class HTMLSelectLanguageField extends HTMLSelectField {
 		$this->mParams['default'] ??= $languageCode;
 	}
 }
+
+/** @deprecated since 1.42 */
+class_alias( HTMLSelectLanguageField::class, 'HTMLSelectLanguageField' );
diff --git a/includes/htmlform/fields/HTMLSelectLimitField.php b/includes/htmlform/fields/HTMLSelectLimitField.php
index 80b0560422b..5aac206886e 100644
--- a/includes/htmlform/fields/HTMLSelectLimitField.php
+++ b/includes/htmlform/fields/HTMLSelectLimitField.php
@@ -1,5 +1,7 @@
 <?php
 
+namespace MediaWiki\HTMLForm\Field;
+
 /**
  * A limit dropdown, which accepts any valid number
  *
@@ -35,3 +37,6 @@ class HTMLSelectLimitField extends HTMLSelectField {
 		return true;
 	}
 }
+
+/** @deprecated since 1.42 */
+class_alias( HTMLSelectLimitField::class, 'HTMLSelectLimitField' );
diff --git a/includes/htmlform/fields/HTMLSelectNamespace.php b/includes/htmlform/fields/HTMLSelectNamespace.php
index 1896027fdbf..5f5b96e0af6 100644
--- a/includes/htmlform/fields/HTMLSelectNamespace.php
+++ b/includes/htmlform/fields/HTMLSelectNamespace.php
@@ -1,6 +1,9 @@
 <?php
 
+namespace MediaWiki\HTMLForm\Field;
+
 use MediaWiki\Html\Html;
+use MediaWiki\HTMLForm\HTMLFormField;
 
 /**
  * Wrapper for Html::namespaceSelector to use in HTMLForm
@@ -52,7 +55,7 @@ class HTMLSelectNamespace extends HTMLFormField {
 	 * @stable to override
 	 */
 	public function getInputOOUI( $value ) {
-		return new MediaWiki\Widget\NamespaceInputWidget( [
+		return new \MediaWiki\Widget\NamespaceInputWidget( [
 			'value' => $value,
 			'name' => $this->mName,
 			'id' => $this->mID,
@@ -78,3 +81,6 @@ class HTMLSelectNamespace extends HTMLFormField {
 		return true;
 	}
 }
+
+/** @deprecated since 1.42 */
+class_alias( HTMLSelectNamespace::class, 'HTMLSelectNamespace' );
diff --git a/includes/htmlform/fields/HTMLSelectNamespaceWithButton.php b/includes/htmlform/fields/HTMLSelectNamespaceWithButton.php
index efbc9b7d22b..1c95e76a96f 100644
--- a/includes/htmlform/fields/HTMLSelectNamespaceWithButton.php
+++ b/includes/htmlform/fields/HTMLSelectNamespaceWithButton.php
@@ -1,4 +1,9 @@
 <?php
+
+namespace MediaWiki\HTMLForm\Field;
+
+use MediaWiki\HTMLForm\HTMLFormActionFieldLayout;
+
 /**
  * Creates a Html::namespaceSelector input field with a button assigned to the input field.
  *
@@ -26,3 +31,6 @@ class HTMLSelectNamespaceWithButton extends HTMLSelectNamespace {
 		return new HTMLFormActionFieldLayout( $inputField, $buttonWidget, $config );
 	}
 }
+
+/** @deprecated since 1.42 */
+class_alias( HTMLSelectNamespaceWithButton::class, 'HTMLSelectNamespaceWithButton' );
diff --git a/includes/htmlform/fields/HTMLSelectOrOtherField.php b/includes/htmlform/fields/HTMLSelectOrOtherField.php
index ffb814babb6..4a5bd061398 100644
--- a/includes/htmlform/fields/HTMLSelectOrOtherField.php
+++ b/includes/htmlform/fields/HTMLSelectOrOtherField.php
@@ -1,7 +1,11 @@
 <?php
 
+namespace MediaWiki\HTMLForm\Field;
+
 use MediaWiki\Html\Html;
+use MediaWiki\HTMLForm\HTMLFormField;
 use MediaWiki\Request\WebRequest;
+use XmlSelect;
 
 /**
  * Select dropdown field, with an additional "other" textbox.
@@ -113,7 +117,7 @@ class HTMLSelectOrOtherField extends HTMLTextField {
 			'tabindex',
 		];
 
-		$dropdownAttribs += OOUI\Element::configFromHtmlAttributes(
+		$dropdownAttribs += \OOUI\Element::configFromHtmlAttributes(
 			$this->getAttributes( $allowedParams )
 		);
 
@@ -134,7 +138,7 @@ class HTMLSelectOrOtherField extends HTMLTextField {
 			'minlength',
 		];
 
-		$textAttribs += OOUI\Element::configFromHtmlAttributes(
+		$textAttribs += \OOUI\Element::configFromHtmlAttributes(
 			$this->getAttributes( $allowedParams )
 		);
 
@@ -163,7 +167,7 @@ class HTMLSelectOrOtherField extends HTMLTextField {
 	}
 
 	public function getInputWidget( $params ) {
-		return new MediaWiki\Widget\SelectWithInputWidget( $params );
+		return new \MediaWiki\Widget\SelectWithInputWidget( $params );
 	}
 
 	/**
@@ -197,3 +201,6 @@ class HTMLSelectOrOtherField extends HTMLTextField {
 		return [ self::FIELD_CLASS ];
 	}
 }
+
+/** @deprecated since 1.42 */
+class_alias( HTMLSelectOrOtherField::class, 'HTMLSelectOrOtherField' );
diff --git a/includes/htmlform/fields/HTMLSizeFilterField.php b/includes/htmlform/fields/HTMLSizeFilterField.php
index 7109e5c7a22..af7dbacb3f5 100644
--- a/includes/htmlform/fields/HTMLSizeFilterField.php
+++ b/includes/htmlform/fields/HTMLSizeFilterField.php
@@ -1,6 +1,10 @@
 <?php
 
+namespace MediaWiki\HTMLForm\Field;
+
 use MediaWiki\Request\WebRequest;
+use MediaWiki\Widget\SizeFilterWidget;
+use Xml;
 
 /**
  * A size filter field for use on query-type special pages. It looks a bit like:
@@ -60,7 +64,7 @@ class HTMLSizeFilterField extends HTMLIntField {
 		$value = $params['value'];
 		$params['value'] = $value ? abs( $value ) : '';
 
-		return new MediaWiki\Widget\SizeFilterWidget( [
+		return new SizeFilterWidget( [
 			'selectMin' => $this->mSelectMin,
 			'textinput' => $params,
 			'radioselectinput' => [
@@ -95,3 +99,6 @@ class HTMLSizeFilterField extends HTMLIntField {
 		return false;
 	}
 }
+
+/** @deprecated since 1.42 */
+class_alias( HTMLSizeFilterField::class, 'HTMLSizeFilterField' );
diff --git a/includes/htmlform/fields/HTMLSubmitField.php b/includes/htmlform/fields/HTMLSubmitField.php
index 1dadae62a7c..ad5877f0732 100644
--- a/includes/htmlform/fields/HTMLSubmitField.php
+++ b/includes/htmlform/fields/HTMLSubmitField.php
@@ -1,5 +1,7 @@
 <?php
 
+namespace MediaWiki\HTMLForm\Field;
+
 /**
  * Add a submit button inline in the form (as opposed to
  * HTMLForm::addButton(), which will add it at the end).
@@ -19,3 +21,6 @@ class HTMLSubmitField extends HTMLButtonField {
 		return $request->getCheck( $this->mName );
 	}
 }
+
+/** @deprecated since 1.42 */
+class_alias( HTMLSubmitField::class, 'HTMLSubmitField' );
diff --git a/includes/htmlform/fields/HTMLTagFilter.php b/includes/htmlform/fields/HTMLTagFilter.php
index dcdce17af4e..64492926e48 100644
--- a/includes/htmlform/fields/HTMLTagFilter.php
+++ b/includes/htmlform/fields/HTMLTagFilter.php
@@ -1,4 +1,10 @@
 <?php
+
+namespace MediaWiki\HTMLForm\Field;
+
+use ChangeTags;
+use MediaWiki\HTMLForm\HTMLFormField;
+
 /**
  * Wrapper for ChangeTags::buildTagFilterSelector to use in HTMLForm
  *
@@ -31,7 +37,7 @@ class HTMLTagFilter extends HTMLFormField {
 		if ( $this->tagFilter ) {
 			return parent::getOOUI( $value );
 		}
-		return new OOUI\FieldLayout( new OOUI\Widget() );
+		return new \OOUI\FieldLayout( new \OOUI\Widget() );
 	}
 
 	public function getInputHTML( $value ) {
@@ -54,3 +60,6 @@ class HTMLTagFilter extends HTMLFormField {
 		return true;
 	}
 }
+
+/** @deprecated since 1.42 */
+class_alias( HTMLTagFilter::class, 'HTMLTagFilter' );
diff --git a/includes/htmlform/fields/HTMLTagMultiselectField.php b/includes/htmlform/fields/HTMLTagMultiselectField.php
index 3b6d27ab2e0..c0a1bf0e792 100644
--- a/includes/htmlform/fields/HTMLTagMultiselectField.php
+++ b/includes/htmlform/fields/HTMLTagMultiselectField.php
@@ -1,5 +1,7 @@
 <?php
 
+namespace MediaWiki\HTMLForm\Field;
+
 use MediaWiki\Widget\TagMultiselectWidget;
 
 /**
@@ -131,3 +133,6 @@ class HTMLTagMultiselectField extends HTMLTextField {
 	}
 
 }
+
+/** @deprecated since 1.42 */
+class_alias( HTMLTagMultiselectField::class, 'HTMLTagMultiselectField' );
diff --git a/includes/htmlform/fields/HTMLTextAreaField.php b/includes/htmlform/fields/HTMLTextAreaField.php
index 6477bb8d235..7e1243a7a27 100644
--- a/includes/htmlform/fields/HTMLTextAreaField.php
+++ b/includes/htmlform/fields/HTMLTextAreaField.php
@@ -1,12 +1,15 @@
 <?php
 
+namespace MediaWiki\HTMLForm\Field;
+
+use InvalidArgumentException;
+use MediaWiki\Html\Html;
+use MediaWiki\HTMLForm\HTMLFormField;
+use MediaWiki\MediaWikiServices;
+
 /*
  * @stable to extend
  */
-
-use MediaWiki\Html\Html;
-use MediaWiki\MediaWikiServices;
-
 class HTMLTextAreaField extends HTMLFormField {
 	protected const DEFAULT_COLS = 80;
 	protected const DEFAULT_ROWS = 25;
@@ -145,11 +148,11 @@ class HTMLTextAreaField extends HTMLFormField {
 			'autofocus',
 		];
 
-		$attribs += OOUI\Element::configFromHtmlAttributes(
+		$attribs += \OOUI\Element::configFromHtmlAttributes(
 			$this->getAttributes( $allowedParams )
 		);
 
-		return new OOUI\MultilineTextInputWidget( [
+		return new \OOUI\MultilineTextInputWidget( [
 			'id' => $this->mID,
 			'name' => $this->mName,
 			'value' => $value,
@@ -157,3 +160,6 @@ class HTMLTextAreaField extends HTMLFormField {
 		] + $attribs );
 	}
 }
+
+/** @deprecated since 1.42 */
+class_alias( HTMLTextAreaField::class, 'HTMLTextAreaField' );
diff --git a/includes/htmlform/fields/HTMLTextField.php b/includes/htmlform/fields/HTMLTextField.php
index 13674fd3b3e..4d3733319cf 100644
--- a/includes/htmlform/fields/HTMLTextField.php
+++ b/includes/htmlform/fields/HTMLTextField.php
@@ -1,6 +1,10 @@
 <?php
 
+namespace MediaWiki\HTMLForm\Field;
+
 use MediaWiki\Html\Html;
+use MediaWiki\HTMLForm\CodexHTMLForm;
+use MediaWiki\HTMLForm\HTMLFormField;
 use OOUI\Widget;
 
 /**
@@ -207,7 +211,7 @@ class HTMLTextField extends HTMLFormField {
 			'indicator',
 		];
 
-		$attribs += OOUI\Element::configFromHtmlAttributes(
+		$attribs += \OOUI\Element::configFromHtmlAttributes(
 			$this->getAttributes( $allowedParams )
 		);
 
@@ -233,7 +237,7 @@ class HTMLTextField extends HTMLFormField {
 	 * @return Widget
 	 */
 	protected function getInputWidget( $params ) {
-		return new OOUI\TextInputWidget( $params );
+		return new \OOUI\TextInputWidget( $params );
 	}
 
 	/**
@@ -246,3 +250,6 @@ class HTMLTextField extends HTMLFormField {
 		return [];
 	}
 }
+
+/** @deprecated since 1.42 */
+class_alias( HTMLTextField::class, 'HTMLTextField' );
diff --git a/includes/htmlform/fields/HTMLTextFieldWithButton.php b/includes/htmlform/fields/HTMLTextFieldWithButton.php
index 24fbc9e4ee8..af41f968e13 100644
--- a/includes/htmlform/fields/HTMLTextFieldWithButton.php
+++ b/includes/htmlform/fields/HTMLTextFieldWithButton.php
@@ -1,4 +1,9 @@
 <?php
+
+namespace MediaWiki\HTMLForm\Field;
+
+use MediaWiki\HTMLForm\HTMLFormActionFieldLayout;
+
 /**
  * Creates a text input field with a button assigned to the input field.
  *
@@ -26,3 +31,6 @@ class HTMLTextFieldWithButton extends HTMLTextField {
 		return new HTMLFormActionFieldLayout( $inputField, $buttonWidget, $config );
 	}
 }
+
+/** @deprecated since 1.42 */
+class_alias( HTMLTextFieldWithButton::class, 'HTMLTextFieldWithButton' );
diff --git a/includes/htmlform/fields/HTMLTimezoneField.php b/includes/htmlform/fields/HTMLTimezoneField.php
index 63e7f8e3c9b..9b4a26e034d 100644
--- a/includes/htmlform/fields/HTMLTimezoneField.php
+++ b/includes/htmlform/fields/HTMLTimezoneField.php
@@ -1,5 +1,10 @@
 <?php
 
+namespace MediaWiki\HTMLForm\Field;
+
+use DateTime;
+use DateTimeZone;
+use InvalidArgumentException;
 use MediaWiki\Context\RequestContext;
 use MediaWiki\MainConfigNames;
 use MediaWiki\MediaWikiServices;
@@ -164,3 +169,6 @@ class HTMLTimezoneField extends HTMLSelectOrOtherField {
 		return $classes;
 	}
 }
+
+/** @deprecated since 1.42 */
+class_alias( HTMLTimezoneField::class, 'HTMLTimezoneField' );
diff --git a/includes/htmlform/fields/HTMLTitleTextField.php b/includes/htmlform/fields/HTMLTitleTextField.php
index fa67a4f8d60..5cd32f2b26e 100644
--- a/includes/htmlform/fields/HTMLTitleTextField.php
+++ b/includes/htmlform/fields/HTMLTitleTextField.php
@@ -1,5 +1,9 @@
 <?php
 
+namespace MediaWiki\HTMLForm\Field;
+
+use FormatJson;
+use InvalidArgumentException;
 use MediaWiki\MediaWikiServices;
 use MediaWiki\Title\MalformedTitleException;
 use MediaWiki\Title\Title;
@@ -128,3 +132,6 @@ class HTMLTitleTextField extends HTMLTextField {
 		];
 	}
 }
+
+/** @deprecated since 1.42 */
+class_alias( HTMLTitleTextField::class, 'HTMLTitleTextField' );
diff --git a/includes/htmlform/fields/HTMLTitlesMultiselectField.php b/includes/htmlform/fields/HTMLTitlesMultiselectField.php
index 78b9a20cf7a..9a1be38496b 100644
--- a/includes/htmlform/fields/HTMLTitlesMultiselectField.php
+++ b/includes/htmlform/fields/HTMLTitlesMultiselectField.php
@@ -1,5 +1,7 @@
 <?php
 
+namespace MediaWiki\HTMLForm\Field;
+
 use MediaWiki\Widget\TitlesMultiselectWidget;
 
 /**
@@ -145,3 +147,6 @@ class HTMLTitlesMultiselectField extends HTMLTitleTextField {
 	}
 
 }
+
+/** @deprecated since 1.42 */
+class_alias( HTMLTitlesMultiselectField::class, 'HTMLTitlesMultiselectField' );
diff --git a/includes/htmlform/fields/HTMLToggleSwitchField.php b/includes/htmlform/fields/HTMLToggleSwitchField.php
index 807437bca30..111a04c42f5 100644
--- a/includes/htmlform/fields/HTMLToggleSwitchField.php
+++ b/includes/htmlform/fields/HTMLToggleSwitchField.php
@@ -1,5 +1,7 @@
 <?php
 
+namespace MediaWiki\HTMLForm\Field;
+
 use MediaWiki\Widget\ToggleSwitchWidget;
 
 class HTMLToggleSwitchField extends HTMLCheckField {
@@ -20,7 +22,7 @@ class HTMLToggleSwitchField extends HTMLCheckField {
 		$attr['id'] = $this->mID;
 		$attr['name'] = $this->mName;
 
-		$attr += OOUI\Element::configFromHtmlAttributes(
+		$attr += \OOUI\Element::configFromHtmlAttributes(
 			$this->getAttributes( [ 'disabled', 'tabindex' ] )
 		);
 
@@ -47,3 +49,6 @@ class HTMLToggleSwitchField extends HTMLCheckField {
 		return [ 'mediawiki.widgets.ToggleSwitchWidget' ];
 	}
 }
+
+/** @deprecated since 1.42 */
+class_alias( HTMLToggleSwitchField::class, 'HTMLToggleSwitchField' );
diff --git a/includes/htmlform/fields/HTMLUserTextField.php b/includes/htmlform/fields/HTMLUserTextField.php
index f6348e30ee3..4b2eea2e09f 100644
--- a/includes/htmlform/fields/HTMLUserTextField.php
+++ b/includes/htmlform/fields/HTMLUserTextField.php
@@ -1,5 +1,7 @@
 <?php
 
+namespace MediaWiki\HTMLForm\Field;
+
 use MediaWiki\MediaWikiServices;
 use MediaWiki\User\ExternalUserNames;
 use MediaWiki\Widget\UserInputWidget;
@@ -147,3 +149,6 @@ class HTMLUserTextField extends HTMLTextField {
 		return parent::getInputHTML( $value );
 	}
 }
+
+/** @deprecated since 1.42 */
+class_alias( HTMLUserTextField::class, 'HTMLUserTextField' );
diff --git a/includes/htmlform/fields/HTMLUsersMultiselectField.php b/includes/htmlform/fields/HTMLUsersMultiselectField.php
index 561fdda7b0a..7ec7bcff236 100644
--- a/includes/htmlform/fields/HTMLUsersMultiselectField.php
+++ b/includes/htmlform/fields/HTMLUsersMultiselectField.php
@@ -1,5 +1,7 @@
 <?php
 
+namespace MediaWiki\HTMLForm\Field;
+
 use MediaWiki\MediaWikiServices;
 use MediaWiki\User\UserRigorOptions;
 use MediaWiki\Widget\UsersMultiselectWidget;
@@ -156,3 +158,6 @@ class HTMLUsersMultiselectField extends HTMLUserTextField {
 	}
 
 }
+
+/** @deprecated since 1.42 */
+class_alias( HTMLUsersMultiselectField::class, 'HTMLUsersMultiselectField' );
diff --git a/includes/page/ProtectionForm.php b/includes/page/ProtectionForm.php
index 0d5753c9397..cbce6c58c12 100644
--- a/includes/page/ProtectionForm.php
+++ b/includes/page/ProtectionForm.php
@@ -27,7 +27,6 @@ namespace MediaWiki\Page;
 
 use Article;
 use ErrorPageError;
-use HTMLForm;
 use Language;
 use LogEventsList;
 use LogPage;
@@ -35,6 +34,7 @@ use MediaWiki\CommentStore\CommentStore;
 use MediaWiki\Context\IContextSource;
 use MediaWiki\HookContainer\HookRunner;
 use MediaWiki\Html\Html;
+use MediaWiki\HTMLForm\HTMLForm;
 use MediaWiki\MediaWikiServices;
 use MediaWiki\Output\OutputPage;
 use MediaWiki\Permissions\Authority;
diff --git a/includes/preferences/DefaultPreferencesFactory.php b/includes/preferences/DefaultPreferencesFactory.php
index b5d7107072c..615a988e1be 100644
--- a/includes/preferences/DefaultPreferencesFactory.php
+++ b/includes/preferences/DefaultPreferencesFactory.php
@@ -20,8 +20,6 @@
 
 namespace MediaWiki\Preferences;
 
-use HTMLForm;
-use HTMLFormField;
 use ILanguageConverter;
 use Language;
 use LanguageCode;
@@ -34,6 +32,9 @@ use MediaWiki\Context\IContextSource;
 use MediaWiki\HookContainer\HookContainer;
 use MediaWiki\HookContainer\HookRunner;
 use MediaWiki\Html\Html;
+use MediaWiki\HTMLForm\HTMLForm;
+use MediaWiki\HTMLForm\HTMLFormField;
+use MediaWiki\HTMLForm\HTMLNestedFilterable;
 use MediaWiki\Languages\LanguageConverterFactory;
 use MediaWiki\Languages\LanguageNameUtils;
 use MediaWiki\Linker\LinkRenderer;
@@ -377,7 +378,7 @@ class DefaultPreferencesFactory implements PreferencesFactory {
 	public static function getPreferenceForField( $name, HTMLFormField $field, array $userOptions ) {
 		$val = $userOptions[$name] ?? null;
 
-		if ( $field instanceof \HTMLNestedFilterable ) {
+		if ( $field instanceof HTMLNestedFilterable ) {
 			$val = [];
 			$prefix = $field->mParams['prefix'] ?? $name;
 			// Fetch all possible preference keys of the given field on this wiki.
diff --git a/includes/preferences/Hook/PreferencesFormPreSaveHook.php b/includes/preferences/Hook/PreferencesFormPreSaveHook.php
index 8b7e5853ae2..2aec90824ef 100644
--- a/includes/preferences/Hook/PreferencesFormPreSaveHook.php
+++ b/includes/preferences/Hook/PreferencesFormPreSaveHook.php
@@ -2,7 +2,7 @@
 
 namespace MediaWiki\Preferences\Hook;
 
-use HTMLForm;
+use MediaWiki\HTMLForm\HTMLForm;
 use MediaWiki\User\User;
 
 /**
diff --git a/includes/preferences/PreferencesFactory.php b/includes/preferences/PreferencesFactory.php
index 75ea2070e88..8acedb68cec 100644
--- a/includes/preferences/PreferencesFactory.php
+++ b/includes/preferences/PreferencesFactory.php
@@ -20,8 +20,8 @@
 
 namespace MediaWiki\Preferences;
 
-use HTMLForm;
 use MediaWiki\Context\IContextSource;
+use MediaWiki\HTMLForm\HTMLForm;
 use MediaWiki\User\User;
 use PreferencesFormOOUI;
 
diff --git a/includes/specialpage/AuthManagerSpecialPage.php b/includes/specialpage/AuthManagerSpecialPage.php
index a978257561a..ff2cce6871d 100644
--- a/includes/specialpage/AuthManagerSpecialPage.php
+++ b/includes/specialpage/AuthManagerSpecialPage.php
@@ -3,7 +3,6 @@
 namespace MediaWiki\SpecialPage;
 
 use ErrorPageError;
-use HTMLForm;
 use HTMLInfoField;
 use InvalidArgumentException;
 use LogicException;
@@ -11,6 +10,7 @@ use MediaWiki\Auth\AuthenticationRequest;
 use MediaWiki\Auth\AuthenticationResponse;
 use MediaWiki\Auth\AuthManager;
 use MediaWiki\Context\DerivativeContext;
+use MediaWiki\HTMLForm\HTMLForm;
 use MediaWiki\Language\RawMessage;
 use MediaWiki\Logger\LoggerFactory;
 use MediaWiki\Request\DerivativeRequest;
diff --git a/includes/specialpage/FormSpecialPage.php b/includes/specialpage/FormSpecialPage.php
index d4c4813a3dc..e470dc543cb 100644
--- a/includes/specialpage/FormSpecialPage.php
+++ b/includes/specialpage/FormSpecialPage.php
@@ -23,8 +23,8 @@
 
 namespace MediaWiki\SpecialPage;
 
-use HTMLForm;
 use MediaWiki\Context\DerivativeContext;
+use MediaWiki\HTMLForm\HTMLForm;
 use MediaWiki\Request\DerivativeRequest;
 use MediaWiki\Status\Status;
 use MediaWiki\User\User;
diff --git a/includes/specialpage/Hook/SpecialPageBeforeFormDisplayHook.php b/includes/specialpage/Hook/SpecialPageBeforeFormDisplayHook.php
index f55c2365e45..025eac9e031 100644
--- a/includes/specialpage/Hook/SpecialPageBeforeFormDisplayHook.php
+++ b/includes/specialpage/Hook/SpecialPageBeforeFormDisplayHook.php
@@ -2,7 +2,7 @@
 
 namespace MediaWiki\SpecialPage\Hook;
 
-use HTMLForm;
+use MediaWiki\HTMLForm\HTMLForm;
 
 /**
  * This is a hook handler interface, see docs/Hooks.md.
diff --git a/includes/specialpage/LoginSignupSpecialPage.php b/includes/specialpage/LoginSignupSpecialPage.php
index 4ac9b6873cc..55ee40d643d 100644
--- a/includes/specialpage/LoginSignupSpecialPage.php
+++ b/includes/specialpage/LoginSignupSpecialPage.php
@@ -26,7 +26,6 @@ namespace MediaWiki\SpecialPage;
 use ErrorPageError;
 use Exception;
 use FatalError;
-use HTMLForm;
 use LogicException;
 use LoginHelper;
 use MediaWiki\Auth\AuthenticationRequest;
@@ -36,6 +35,7 @@ use MediaWiki\Auth\PasswordAuthenticationRequest;
 use MediaWiki\Context\DerivativeContext;
 use MediaWiki\Context\RequestContext;
 use MediaWiki\Html\Html;
+use MediaWiki\HTMLForm\HTMLForm;
 use MediaWiki\Language\RawMessage;
 use MediaWiki\Logger\LoggerFactory;
 use MediaWiki\MainConfigNames;
diff --git a/includes/specialpage/SpecialRedirectWithAction.php b/includes/specialpage/SpecialRedirectWithAction.php
index 10a733d95fa..a2bf5e3aaef 100644
--- a/includes/specialpage/SpecialRedirectWithAction.php
+++ b/includes/specialpage/SpecialRedirectWithAction.php
@@ -2,7 +2,7 @@
 
 namespace MediaWiki\SpecialPage;
 
-use HTMLForm;
+use MediaWiki\HTMLForm\HTMLForm;
 use MediaWiki\MediaWikiServices;
 use MediaWiki\Status\Status;
 use MediaWiki\Title\MalformedTitleException;
diff --git a/includes/specials/Hook/EmailUserFormHook.php b/includes/specials/Hook/EmailUserFormHook.php
index 668c6be07b9..36b7c33f1cb 100644
--- a/includes/specials/Hook/EmailUserFormHook.php
+++ b/includes/specials/Hook/EmailUserFormHook.php
@@ -2,7 +2,7 @@
 
 namespace MediaWiki\Hook;
 
-use HTMLForm;
+use MediaWiki\HTMLForm\HTMLForm;
 
 /**
  * This is a hook handler interface, see docs/Hooks.md.
diff --git a/includes/specials/Hook/PreferencesGetLegendHook.php b/includes/specials/Hook/PreferencesGetLegendHook.php
index 88b4aa69987..930e0acbdbf 100644
--- a/includes/specials/Hook/PreferencesGetLegendHook.php
+++ b/includes/specials/Hook/PreferencesGetLegendHook.php
@@ -2,7 +2,7 @@
 
 namespace MediaWiki\Hook;
 
-use HTMLForm;
+use MediaWiki\HTMLForm\HTMLForm;
 
 /**
  * This is a hook handler interface, see docs/Hooks.md.
diff --git a/includes/specials/SpecialActiveUsers.php b/includes/specials/SpecialActiveUsers.php
index 8e8d08cf9d5..83e79327374 100644
--- a/includes/specials/SpecialActiveUsers.php
+++ b/includes/specials/SpecialActiveUsers.php
@@ -23,11 +23,11 @@
 
 namespace MediaWiki\Specials;
 
-use HTMLForm;
 use MediaWiki\Block\HideUserUtils;
 use MediaWiki\Cache\LinkBatchFactory;
 use MediaWiki\Html\FormOptions;
 use MediaWiki\Html\Html;
+use MediaWiki\HTMLForm\HTMLForm;
 use MediaWiki\MainConfigNames;
 use MediaWiki\Pager\ActiveUsersPager;
 use MediaWiki\SpecialPage\SpecialPage;
diff --git a/includes/specials/SpecialAllMessages.php b/includes/specials/SpecialAllMessages.php
index 45c4784e5c6..3f963e50468 100644
--- a/includes/specials/SpecialAllMessages.php
+++ b/includes/specials/SpecialAllMessages.php
@@ -23,10 +23,10 @@
 
 namespace MediaWiki\Specials;
 
-use HTMLForm;
 use LocalisationCache;
 use MediaWiki\Html\FormOptions;
 use MediaWiki\Html\Html;
+use MediaWiki\HTMLForm\HTMLForm;
 use MediaWiki\Languages\LanguageFactory;
 use MediaWiki\Languages\LanguageNameUtils;
 use MediaWiki\MainConfigNames;
diff --git a/includes/specials/SpecialAllPages.php b/includes/specials/SpecialAllPages.php
index e1a741755c1..75539559f1f 100644
--- a/includes/specials/SpecialAllPages.php
+++ b/includes/specials/SpecialAllPages.php
@@ -23,8 +23,8 @@
 
 namespace MediaWiki\Specials;
 
-use HTMLForm;
 use MediaWiki\Html\Html;
+use MediaWiki\HTMLForm\HTMLForm;
 use MediaWiki\MainConfigNames;
 use MediaWiki\MediaWikiServices;
 use MediaWiki\Page\ExistingPageRecord;
diff --git a/includes/specials/SpecialAutoblockList.php b/includes/specials/SpecialAutoblockList.php
index 727369154a3..a33de2a1c4c 100644
--- a/includes/specials/SpecialAutoblockList.php
+++ b/includes/specials/SpecialAutoblockList.php
@@ -23,7 +23,6 @@
 
 namespace MediaWiki\Specials;
 
-use HTMLForm;
 use MediaWiki\Block\BlockActionInfo;
 use MediaWiki\Block\BlockRestrictionStore;
 use MediaWiki\Block\BlockUtils;
@@ -33,6 +32,7 @@ use MediaWiki\CommentFormatter\RowCommentFormatter;
 use MediaWiki\CommentStore\CommentStore;
 use MediaWiki\Config\ConfigException;
 use MediaWiki\Html\Html;
+use MediaWiki\HTMLForm\HTMLForm;
 use MediaWiki\MainConfigNames;
 use MediaWiki\Pager\BlockListPager;
 use MediaWiki\SpecialPage\SpecialPage;
diff --git a/includes/specials/SpecialBlock.php b/includes/specials/SpecialBlock.php
index 8c0e6a2db6a..132a41de0f4 100644
--- a/includes/specials/SpecialBlock.php
+++ b/includes/specials/SpecialBlock.php
@@ -25,7 +25,6 @@ namespace MediaWiki\Specials;
 
 use ErrorPageError;
 use HtmlArmor;
-use HTMLForm;
 use Language;
 use LogEventsList;
 use MediaWiki\Block\BlockActionInfo;
@@ -41,6 +40,7 @@ use MediaWiki\Block\Restriction\PageRestriction;
 use MediaWiki\CommentStore\CommentStore;
 use MediaWiki\Context\IContextSource;
 use MediaWiki\Html\Html;
+use MediaWiki\HTMLForm\HTMLForm;
 use MediaWiki\MainConfigNames;
 use MediaWiki\MediaWikiServices;
 use MediaWiki\Page\PageReference;
diff --git a/includes/specials/SpecialBlockList.php b/includes/specials/SpecialBlockList.php
index 001f60717a5..9da4d37ad8d 100644
--- a/includes/specials/SpecialBlockList.php
+++ b/includes/specials/SpecialBlockList.php
@@ -23,7 +23,6 @@
 
 namespace MediaWiki\Specials;
 
-use HTMLForm;
 use MediaWiki\Block\BlockActionInfo;
 use MediaWiki\Block\BlockRestrictionStore;
 use MediaWiki\Block\BlockUtils;
@@ -35,6 +34,7 @@ use MediaWiki\CommentFormatter\RowCommentFormatter;
 use MediaWiki\CommentStore\CommentStore;
 use MediaWiki\Config\ConfigException;
 use MediaWiki\Html\Html;
+use MediaWiki\HTMLForm\HTMLForm;
 use MediaWiki\MainConfigNames;
 use MediaWiki\Pager\BlockListPager;
 use MediaWiki\SpecialPage\SpecialPage;
diff --git a/includes/specials/SpecialBookSources.php b/includes/specials/SpecialBookSources.php
index 9e0619ad945..1a943938541 100644
--- a/includes/specials/SpecialBookSources.php
+++ b/includes/specials/SpecialBookSources.php
@@ -23,8 +23,8 @@
 
 namespace MediaWiki\Specials;
 
-use HTMLForm;
 use MediaWiki\Html\Html;
+use MediaWiki\HTMLForm\HTMLForm;
 use MediaWiki\Revision\RevisionLookup;
 use MediaWiki\Revision\SlotRecord;
 use MediaWiki\SpecialPage\SpecialPage;
diff --git a/includes/specials/SpecialBotPasswords.php b/includes/specials/SpecialBotPasswords.php
index dd973cf6e80..d834db2038e 100644
--- a/includes/specials/SpecialBotPasswords.php
+++ b/includes/specials/SpecialBotPasswords.php
@@ -24,11 +24,11 @@
 namespace MediaWiki\Specials;
 
 use ErrorPageError;
-use HTMLForm;
 use HTMLRestrictionsField;
 use InvalidPassword;
 use MediaWiki\Auth\AuthManager;
 use MediaWiki\Html\Html;
+use MediaWiki\HTMLForm\HTMLForm;
 use MediaWiki\Logger\LoggerFactory;
 use MediaWiki\MainConfigNames;
 use MediaWiki\Permissions\GrantsInfo;
diff --git a/includes/specials/SpecialChangeContentModel.php b/includes/specials/SpecialChangeContentModel.php
index 4896c09b080..afa2d32e0e9 100644
--- a/includes/specials/SpecialChangeContentModel.php
+++ b/includes/specials/SpecialChangeContentModel.php
@@ -4,13 +4,13 @@ namespace MediaWiki\Specials;
 
 use ContentHandler;
 use ErrorPageError;
-use HTMLForm;
 use LogEventsList;
 use LogPage;
 use MediaWiki\Collation\CollationFactory;
 use MediaWiki\CommentStore\CommentStore;
 use MediaWiki\Content\IContentHandlerFactory;
 use MediaWiki\EditPage\SpamChecker;
+use MediaWiki\HTMLForm\HTMLForm;
 use MediaWiki\Language\RawMessage;
 use MediaWiki\Page\ContentModelChangeFactory;
 use MediaWiki\Page\WikiPageFactory;
diff --git a/includes/specials/SpecialChangeEmail.php b/includes/specials/SpecialChangeEmail.php
index 1a49277b50f..0c15094f7bc 100644
--- a/includes/specials/SpecialChangeEmail.php
+++ b/includes/specials/SpecialChangeEmail.php
@@ -24,9 +24,9 @@
 namespace MediaWiki\Specials;
 
 use ErrorPageError;
-use HTMLForm;
 use MediaWiki\Auth\AuthManager;
 use MediaWiki\Html\Html;
+use MediaWiki\HTMLForm\HTMLForm;
 use MediaWiki\Logger\LoggerFactory;
 use MediaWiki\Parser\Sanitizer;
 use MediaWiki\SpecialPage\FormSpecialPage;
diff --git a/includes/specials/SpecialComparePages.php b/includes/specials/SpecialComparePages.php
index edfbc745f28..8ad43c00620 100644
--- a/includes/specials/SpecialComparePages.php
+++ b/includes/specials/SpecialComparePages.php
@@ -26,8 +26,8 @@
 namespace MediaWiki\Specials;
 
 use DifferenceEngine;
-use HTMLForm;
 use MediaWiki\Content\IContentHandlerFactory;
+use MediaWiki\HTMLForm\HTMLForm;
 use MediaWiki\Revision\RevisionLookup;
 use MediaWiki\Revision\RevisionRecord;
 use MediaWiki\Revision\SlotRecord;
diff --git a/includes/specials/SpecialConfirmEmail.php b/includes/specials/SpecialConfirmEmail.php
index c9d6bd0453f..4a3da813eca 100644
--- a/includes/specials/SpecialConfirmEmail.php
+++ b/includes/specials/SpecialConfirmEmail.php
@@ -23,8 +23,8 @@
 
 namespace MediaWiki\Specials;
 
-use HTMLForm;
 use IDBAccessObject;
+use MediaWiki\HTMLForm\HTMLForm;
 use MediaWiki\Language\RawMessage;
 use MediaWiki\Parser\Sanitizer;
 use MediaWiki\SpecialPage\SpecialPage;
diff --git a/includes/specials/SpecialContributions.php b/includes/specials/SpecialContributions.php
index 26bfcfd7817..d10dd1d5122 100644
--- a/includes/specials/SpecialContributions.php
+++ b/includes/specials/SpecialContributions.php
@@ -23,7 +23,6 @@
 
 namespace MediaWiki\Specials;
 
-use HTMLForm;
 use HTMLMultiSelectField;
 use LogEventsList;
 use MediaWiki\Block\Block;
@@ -32,6 +31,7 @@ use MediaWiki\Cache\LinkBatchFactory;
 use MediaWiki\CommentFormatter\CommentFormatter;
 use MediaWiki\HookContainer\HookRunner;
 use MediaWiki\Html\Html;
+use MediaWiki\HTMLForm\HTMLForm;
 use MediaWiki\MainConfigNames;
 use MediaWiki\MediaWikiServices;
 use MediaWiki\Pager\ContribsPager;
diff --git a/includes/specials/SpecialDeletedContributions.php b/includes/specials/SpecialDeletedContributions.php
index d58e9a10f6c..63833dcdfc5 100644
--- a/includes/specials/SpecialDeletedContributions.php
+++ b/includes/specials/SpecialDeletedContributions.php
@@ -23,13 +23,13 @@
 
 namespace MediaWiki\Specials;
 
-use HTMLForm;
 use LogEventsList;
 use MediaWiki\Block\Block;
 use MediaWiki\Block\DatabaseBlockStore;
 use MediaWiki\Cache\LinkBatchFactory;
 use MediaWiki\CommentFormatter\CommentFormatter;
 use MediaWiki\Html\FormOptions;
+use MediaWiki\HTMLForm\HTMLForm;
 use MediaWiki\MainConfigNames;
 use MediaWiki\Pager\DeletedContribsPager;
 use MediaWiki\Permissions\PermissionManager;
diff --git a/includes/specials/SpecialDiff.php b/includes/specials/SpecialDiff.php
index f7b42d27332..5e363205c8e 100644
--- a/includes/specials/SpecialDiff.php
+++ b/includes/specials/SpecialDiff.php
@@ -24,7 +24,7 @@
 
 namespace MediaWiki\Specials;
 
-use HTMLForm;
+use MediaWiki\HTMLForm\HTMLForm;
 use MediaWiki\SpecialPage\RedirectSpecialPage;
 use MediaWiki\Title\Title;
 
diff --git a/includes/specials/SpecialEditWatchlist.php b/includes/specials/SpecialEditWatchlist.php
index 212d4928104..241d78f5f97 100644
--- a/includes/specials/SpecialEditWatchlist.php
+++ b/includes/specials/SpecialEditWatchlist.php
@@ -31,11 +31,12 @@ namespace MediaWiki\Specials;
 use EditWatchlistCheckboxSeriesField;
 use EditWatchlistNormalHTMLForm;
 use GenderCache;
-use HTMLForm;
 use LogicException;
 use MediaWiki\Cache\LinkBatchFactory;
 use MediaWiki\Deferred\DeferredUpdates;
 use MediaWiki\Html\Html;
+use MediaWiki\HTMLForm\HTMLForm;
+use MediaWiki\HTMLForm\OOUIHTMLForm;
 use MediaWiki\Linker\LinkRenderer;
 use MediaWiki\Linker\LinkTarget;
 use MediaWiki\MainConfigNames;
@@ -53,7 +54,6 @@ use MediaWiki\Title\Title;
 use MediaWiki\Title\TitleParser;
 use MediaWiki\Title\TitleValue;
 use MediaWiki\Watchlist\WatchlistManager;
-use OOUIHTMLForm;
 use Parser;
 use UserNotLoggedIn;
 use WatchedItemStore;
diff --git a/includes/specials/SpecialEmailUser.php b/includes/specials/SpecialEmailUser.php
index 5a289d8eab7..82380e11453 100644
--- a/includes/specials/SpecialEmailUser.php
+++ b/includes/specials/SpecialEmailUser.php
@@ -24,9 +24,9 @@
 namespace MediaWiki\Specials;
 
 use ErrorPageError;
-use HTMLForm;
 use MediaWiki\Config\Config;
 use MediaWiki\Context\IContextSource;
+use MediaWiki\HTMLForm\HTMLForm;
 use MediaWiki\Mail\EmailUserFactory;
 use MediaWiki\MainConfigNames;
 use MediaWiki\MediaWikiServices;
diff --git a/includes/specials/SpecialExpandTemplates.php b/includes/specials/SpecialExpandTemplates.php
index 81ab0e6581d..6aaa511cc26 100644
--- a/includes/specials/SpecialExpandTemplates.php
+++ b/includes/specials/SpecialExpandTemplates.php
@@ -23,8 +23,8 @@
 
 namespace MediaWiki\Specials;
 
-use HTMLForm;
 use MediaWiki\Html\Html;
+use MediaWiki\HTMLForm\HTMLForm;
 use MediaWiki\MainConfigNames;
 use MediaWiki\Output\OutputPage;
 use MediaWiki\Parser\ParserOutput;
diff --git a/includes/specials/SpecialExport.php b/includes/specials/SpecialExport.php
index 29cfdc945b1..d9427db5349 100644
--- a/includes/specials/SpecialExport.php
+++ b/includes/specials/SpecialExport.php
@@ -25,9 +25,9 @@
 
 namespace MediaWiki\Specials;
 
-use HTMLForm;
 use HTMLTextAreaField;
 use MediaWiki\Export\WikiExporterFactory;
+use MediaWiki\HTMLForm\HTMLForm;
 use MediaWiki\Linker\LinksMigration;
 use MediaWiki\Logger\LoggerFactory;
 use MediaWiki\MainConfigNames;
diff --git a/includes/specials/SpecialFileDuplicateSearch.php b/includes/specials/SpecialFileDuplicateSearch.php
index ade99d0269d..2fedeaa849c 100644
--- a/includes/specials/SpecialFileDuplicateSearch.php
+++ b/includes/specials/SpecialFileDuplicateSearch.php
@@ -26,9 +26,9 @@
 namespace MediaWiki\Specials;
 
 use File;
-use HTMLForm;
 use ILanguageConverter;
 use MediaWiki\Cache\LinkBatchFactory;
+use MediaWiki\HTMLForm\HTMLForm;
 use MediaWiki\Languages\LanguageConverterFactory;
 use MediaWiki\Linker\Linker;
 use MediaWiki\SpecialPage\SpecialPage;
diff --git a/includes/specials/SpecialImport.php b/includes/specials/SpecialImport.php
index 03afee02ba2..9a919f625d0 100644
--- a/includes/specials/SpecialImport.php
+++ b/includes/specials/SpecialImport.php
@@ -27,9 +27,9 @@
 namespace MediaWiki\Specials;
 
 use Exception;
-use HTMLForm;
 use ImportReporter;
 use ImportStreamSource;
+use MediaWiki\HTMLForm\HTMLForm;
 use MediaWiki\MainConfigNames;
 use MediaWiki\Permissions\PermissionManager;
 use MediaWiki\SpecialPage\SpecialPage;
diff --git a/includes/specials/SpecialLinkAccounts.php b/includes/specials/SpecialLinkAccounts.php
index 55a5ab8ff4e..cfc8387f1be 100644
--- a/includes/specials/SpecialLinkAccounts.php
+++ b/includes/specials/SpecialLinkAccounts.php
@@ -3,11 +3,11 @@
 namespace MediaWiki\Specials;
 
 use ErrorPageError;
-use HTMLForm;
 use LogicException;
 use MediaWiki\Auth\AuthenticationRequest;
 use MediaWiki\Auth\AuthenticationResponse;
 use MediaWiki\Auth\AuthManager;
+use MediaWiki\HTMLForm\HTMLForm;
 use MediaWiki\MainConfigNames;
 use MediaWiki\SpecialPage\AuthManagerSpecialPage;
 use StatusValue;
diff --git a/includes/specials/SpecialLinkSearch.php b/includes/specials/SpecialLinkSearch.php
index 964e97d193e..2075309f3db 100644
--- a/includes/specials/SpecialLinkSearch.php
+++ b/includes/specials/SpecialLinkSearch.php
@@ -24,9 +24,9 @@
 
 namespace MediaWiki\Specials;
 
-use HTMLForm;
 use MediaWiki\Cache\LinkBatchFactory;
 use MediaWiki\ExternalLinks\LinkFilter;
+use MediaWiki\HTMLForm\HTMLForm;
 use MediaWiki\Linker\Linker;
 use MediaWiki\MainConfigNames;
 use MediaWiki\SpecialPage\QueryPage;
diff --git a/includes/specials/SpecialLockdb.php b/includes/specials/SpecialLockdb.php
index 425d8584db2..d1c4d519fc2 100644
--- a/includes/specials/SpecialLockdb.php
+++ b/includes/specials/SpecialLockdb.php
@@ -24,7 +24,7 @@
 namespace MediaWiki\Specials;
 
 use ErrorPageError;
-use HTMLForm;
+use MediaWiki\HTMLForm\HTMLForm;
 use MediaWiki\MainConfigNames;
 use MediaWiki\SpecialPage\FormSpecialPage;
 use MediaWiki\Status\Status;
diff --git a/includes/specials/SpecialMIMESearch.php b/includes/specials/SpecialMIMESearch.php
index 64652db38a9..4317c596420 100644
--- a/includes/specials/SpecialMIMESearch.php
+++ b/includes/specials/SpecialMIMESearch.php
@@ -26,10 +26,10 @@ namespace MediaWiki\Specials;
 
 use File;
 use HtmlArmor;
-use HTMLForm;
 use ILanguageConverter;
 use LocalFile;
 use MediaWiki\Cache\LinkBatchFactory;
+use MediaWiki\HTMLForm\HTMLForm;
 use MediaWiki\Languages\LanguageConverterFactory;
 use MediaWiki\Linker\Linker;
 use MediaWiki\MediaWikiServices;
diff --git a/includes/specials/SpecialMergeHistory.php b/includes/specials/SpecialMergeHistory.php
index d24edb624b9..40a187ddb32 100644
--- a/includes/specials/SpecialMergeHistory.php
+++ b/includes/specials/SpecialMergeHistory.php
@@ -23,11 +23,11 @@
 
 namespace MediaWiki\Specials;
 
-use HTMLForm;
 use LogEventsList;
 use LogPage;
 use MediaWiki\Cache\LinkBatchFactory;
 use MediaWiki\CommentFormatter\CommentFormatter;
+use MediaWiki\HTMLForm\HTMLForm;
 use MediaWiki\Page\MergeHistoryFactory;
 use MediaWiki\Pager\MergeHistoryPager;
 use MediaWiki\Revision\RevisionStore;
diff --git a/includes/specials/SpecialMute.php b/includes/specials/SpecialMute.php
index 3a79c90df6c..45373bbc451 100644
--- a/includes/specials/SpecialMute.php
+++ b/includes/specials/SpecialMute.php
@@ -22,7 +22,7 @@
 namespace MediaWiki\Specials;
 
 use ErrorPageError;
-use HTMLForm;
+use MediaWiki\HTMLForm\HTMLForm;
 use MediaWiki\MainConfigNames;
 use MediaWiki\Preferences\MultiUsernameFilter;
 use MediaWiki\SpecialPage\FormSpecialPage;
diff --git a/includes/specials/SpecialNewFiles.php b/includes/specials/SpecialNewFiles.php
index 8b0d9c3473b..c7ed5d38bd7 100644
--- a/includes/specials/SpecialNewFiles.php
+++ b/includes/specials/SpecialNewFiles.php
@@ -23,13 +23,13 @@
 
 namespace MediaWiki\Specials;
 
-use HTMLForm;
 use HTMLUserTextField;
 use MediaWiki\Cache\LinkBatchFactory;
 use MediaWiki\Context\DerivativeContext;
 use MediaWiki\Context\IContextSource;
 use MediaWiki\Html\FormOptions;
 use MediaWiki\Html\Html;
+use MediaWiki\HTMLForm\HTMLForm;
 use MediaWiki\Pager\NewFilesPager;
 use MediaWiki\Permissions\GroupPermissionsLookup;
 use MediaWiki\Request\DerivativeRequest;
diff --git a/includes/specials/SpecialNewPages.php b/includes/specials/SpecialNewPages.php
index a067a2f2204..d6dca62813a 100644
--- a/includes/specials/SpecialNewPages.php
+++ b/includes/specials/SpecialNewPages.php
@@ -24,7 +24,6 @@
 namespace MediaWiki\Specials;
 
 use HtmlArmor;
-use HTMLForm;
 use MediaWiki\Cache\LinkBatchFactory;
 use MediaWiki\ChangeTags\ChangeTagsStore;
 use MediaWiki\CommentFormatter\RowCommentFormatter;
@@ -32,6 +31,7 @@ use MediaWiki\Content\IContentHandlerFactory;
 use MediaWiki\Feed\FeedItem;
 use MediaWiki\Html\FormOptions;
 use MediaWiki\Html\Html;
+use MediaWiki\HTMLForm\HTMLForm;
 use MediaWiki\MainConfigNames;
 use MediaWiki\Pager\NewPagesPager;
 use MediaWiki\Permissions\GroupPermissionsLookup;
diff --git a/includes/specials/SpecialNewSection.php b/includes/specials/SpecialNewSection.php
index c2070682a2d..5a929ddb7c8 100644
--- a/includes/specials/SpecialNewSection.php
+++ b/includes/specials/SpecialNewSection.php
@@ -2,7 +2,7 @@
 
 namespace MediaWiki\Specials;
 
-use HTMLForm;
+use MediaWiki\HTMLForm\HTMLForm;
 use MediaWiki\SpecialPage\RedirectSpecialPage;
 use MediaWiki\Title\Title;
 use SearchEngineFactory;
diff --git a/includes/specials/SpecialPageLanguage.php b/includes/specials/SpecialPageLanguage.php
index 9c7b3f5f2d0..d3413ea68af 100644
--- a/includes/specials/SpecialPageLanguage.php
+++ b/includes/specials/SpecialPageLanguage.php
@@ -26,12 +26,12 @@
 namespace MediaWiki\Specials;
 
 use ApiMessage;
-use HTMLForm;
 use LogEventsList;
 use LogPage;
 use ManualLogEntry;
 use MediaWiki\Content\IContentHandlerFactory;
 use MediaWiki\Context\IContextSource;
+use MediaWiki\HTMLForm\HTMLForm;
 use MediaWiki\Language\RawMessage;
 use MediaWiki\Languages\LanguageNameUtils;
 use MediaWiki\MainConfigNames;
diff --git a/includes/specials/SpecialPagesWithProp.php b/includes/specials/SpecialPagesWithProp.php
index af39ce50fd8..0a48b7ea7bc 100644
--- a/includes/specials/SpecialPagesWithProp.php
+++ b/includes/specials/SpecialPagesWithProp.php
@@ -24,8 +24,8 @@
 
 namespace MediaWiki\Specials;
 
-use HTMLForm;
 use MediaWiki\Html\Html;
+use MediaWiki\HTMLForm\HTMLForm;
 use MediaWiki\SpecialPage\QueryPage;
 use MediaWiki\Title\Title;
 use Skin;
diff --git a/includes/specials/SpecialPasswordReset.php b/includes/specials/SpecialPasswordReset.php
index 0053c3d5a89..5c7dbcea1fd 100644
--- a/includes/specials/SpecialPasswordReset.php
+++ b/includes/specials/SpecialPasswordReset.php
@@ -24,7 +24,7 @@
 namespace MediaWiki\Specials;
 
 use ErrorPageError;
-use HTMLForm;
+use MediaWiki\HTMLForm\HTMLForm;
 use MediaWiki\MainConfigNames;
 use MediaWiki\SpecialPage\FormSpecialPage;
 use MediaWiki\Status\Status;
diff --git a/includes/specials/SpecialPermanentLink.php b/includes/specials/SpecialPermanentLink.php
index 9caf5a42b30..4a81b59aea2 100644
--- a/includes/specials/SpecialPermanentLink.php
+++ b/includes/specials/SpecialPermanentLink.php
@@ -23,7 +23,7 @@
 
 namespace MediaWiki\Specials;
 
-use HTMLForm;
+use MediaWiki\HTMLForm\HTMLForm;
 use MediaWiki\SpecialPage\RedirectSpecialPage;
 use MediaWiki\Title\Title;
 
diff --git a/includes/specials/SpecialPreferences.php b/includes/specials/SpecialPreferences.php
index 5888181620d..b594e68a237 100644
--- a/includes/specials/SpecialPreferences.php
+++ b/includes/specials/SpecialPreferences.php
@@ -23,9 +23,9 @@
 
 namespace MediaWiki\Specials;
 
-use HTMLForm;
 use MediaWiki\Context\IContextSource;
 use MediaWiki\Html\Html;
+use MediaWiki\HTMLForm\HTMLForm;
 use MediaWiki\MediaWikiServices;
 use MediaWiki\Preferences\PreferencesFactory;
 use MediaWiki\SpecialPage\SpecialPage;
diff --git a/includes/specials/SpecialPrefixIndex.php b/includes/specials/SpecialPrefixIndex.php
index 007cb1da1a0..fef2b5493f6 100644
--- a/includes/specials/SpecialPrefixIndex.php
+++ b/includes/specials/SpecialPrefixIndex.php
@@ -24,9 +24,9 @@
 namespace MediaWiki\Specials;
 
 use HTMLCheckField;
-use HTMLForm;
 use LinkCache;
 use MediaWiki\Html\Html;
+use MediaWiki\HTMLForm\HTMLForm;
 use MediaWiki\Title\Title;
 use Wikimedia\Rdbms\IConnectionProvider;
 use Wikimedia\Rdbms\IExpression;
diff --git a/includes/specials/SpecialProtectedPages.php b/includes/specials/SpecialProtectedPages.php
index 83406de0d1f..94fb8e1f985 100644
--- a/includes/specials/SpecialProtectedPages.php
+++ b/includes/specials/SpecialProtectedPages.php
@@ -23,13 +23,13 @@
 
 namespace MediaWiki\Specials;
 
-use HTMLForm;
 use HTMLMultiSelectField;
 use HTMLSelectNamespace;
 use HTMLSizeFilterField;
 use MediaWiki\Cache\LinkBatchFactory;
 use MediaWiki\CommentFormatter\RowCommentFormatter;
 use MediaWiki\CommentStore\CommentStore;
+use MediaWiki\HTMLForm\HTMLForm;
 use MediaWiki\MainConfigNames;
 use MediaWiki\Pager\ProtectedPagesPager;
 use MediaWiki\Permissions\RestrictionStore;
diff --git a/includes/specials/SpecialProtectedTitles.php b/includes/specials/SpecialProtectedTitles.php
index 93248d107f3..9e0832ee0ad 100644
--- a/includes/specials/SpecialProtectedTitles.php
+++ b/includes/specials/SpecialProtectedTitles.php
@@ -23,9 +23,9 @@
 
 namespace MediaWiki\Specials;
 
-use HTMLForm;
 use HTMLSelectNamespace;
 use MediaWiki\Cache\LinkBatchFactory;
+use MediaWiki\HTMLForm\HTMLForm;
 use MediaWiki\MainConfigNames;
 use MediaWiki\Pager\ProtectedTitlesPager;
 use MediaWiki\SpecialPage\SpecialPage;
diff --git a/includes/specials/SpecialRandomInCategory.php b/includes/specials/SpecialRandomInCategory.php
index 45127f98db3..2fcaf680522 100644
--- a/includes/specials/SpecialRandomInCategory.php
+++ b/includes/specials/SpecialRandomInCategory.php
@@ -21,7 +21,7 @@
 namespace MediaWiki\Specials;
 
 use BadMethodCallException;
-use HTMLForm;
+use MediaWiki\HTMLForm\HTMLForm;
 use MediaWiki\SpecialPage\FormSpecialPage;
 use MediaWiki\Status\Status;
 use MediaWiki\Title\Title;
diff --git a/includes/specials/SpecialRedirect.php b/includes/specials/SpecialRedirect.php
index 048f95cd0f3..9a4c6c58bb0 100644
--- a/includes/specials/SpecialRedirect.php
+++ b/includes/specials/SpecialRedirect.php
@@ -23,7 +23,7 @@
 
 namespace MediaWiki\Specials;
 
-use HTMLForm;
+use MediaWiki\HTMLForm\HTMLForm;
 use MediaWiki\SpecialPage\FormSpecialPage;
 use MediaWiki\Status\Status;
 use MediaWiki\Title\MalformedTitleException;
diff --git a/includes/specials/SpecialRenameUser.php b/includes/specials/SpecialRenameUser.php
index 5e10b069cd2..af0ac996a2b 100644
--- a/includes/specials/SpecialRenameUser.php
+++ b/includes/specials/SpecialRenameUser.php
@@ -2,10 +2,10 @@
 
 namespace MediaWiki\Specials;
 
-use HTMLForm;
 use Language;
 use MediaWiki\CommentStore\CommentStore;
 use MediaWiki\Html\Html;
+use MediaWiki\HTMLForm\HTMLForm;
 use MediaWiki\Page\MovePageFactory;
 use MediaWiki\Permissions\PermissionManager;
 use MediaWiki\RenameUser\RenameuserSQL;
diff --git a/includes/specials/SpecialResetTokens.php b/includes/specials/SpecialResetTokens.php
index 8104e676580..d68dfdfd9ec 100644
--- a/includes/specials/SpecialResetTokens.php
+++ b/includes/specials/SpecialResetTokens.php
@@ -23,8 +23,8 @@
 
 namespace MediaWiki\Specials;
 
-use HTMLForm;
 use MediaWiki\Html\Html;
+use MediaWiki\HTMLForm\HTMLForm;
 use MediaWiki\MainConfigNames;
 use MediaWiki\SpecialPage\FormSpecialPage;
 use MediaWiki\SpecialPage\SpecialPage;
diff --git a/includes/specials/SpecialRevisionDelete.php b/includes/specials/SpecialRevisionDelete.php
index 25ec05ffd4b..f1b8431c116 100644
--- a/includes/specials/SpecialRevisionDelete.php
+++ b/includes/specials/SpecialRevisionDelete.php
@@ -25,11 +25,11 @@ namespace MediaWiki\Specials;
 
 use ErrorPageError;
 use File;
-use HTMLForm;
 use LogEventsList;
 use LogPage;
 use MediaWiki\CommentStore\CommentStore;
 use MediaWiki\Html\Html;
+use MediaWiki\HTMLForm\HTMLForm;
 use MediaWiki\Permissions\PermissionManager;
 use MediaWiki\Revision\RevisionRecord;
 use MediaWiki\SpecialPage\SpecialPage;
diff --git a/includes/specials/SpecialTags.php b/includes/specials/SpecialTags.php
index 811a660d4d7..94d71b6f86f 100644
--- a/includes/specials/SpecialTags.php
+++ b/includes/specials/SpecialTags.php
@@ -24,9 +24,9 @@
 namespace MediaWiki\Specials;
 
 use ChangeTags;
-use HTMLForm;
 use MediaWiki\ChangeTags\ChangeTagsStore;
 use MediaWiki\CommentStore\CommentStore;
+use MediaWiki\HTMLForm\HTMLForm;
 use MediaWiki\MainConfigNames;
 use MediaWiki\SpecialPage\SpecialPage;
 use PermissionsError;
diff --git a/includes/specials/SpecialUnblock.php b/includes/specials/SpecialUnblock.php
index c970e36b281..bbc3a481f53 100644
--- a/includes/specials/SpecialUnblock.php
+++ b/includes/specials/SpecialUnblock.php
@@ -23,12 +23,12 @@
 
 namespace MediaWiki\Specials;
 
-use HTMLForm;
 use LogEventsList;
 use MediaWiki\Block\Block;
 use MediaWiki\Block\BlockUtils;
 use MediaWiki\Block\DatabaseBlockStore;
 use MediaWiki\Block\UnblockUserFactory;
+use MediaWiki\HTMLForm\HTMLForm;
 use MediaWiki\Request\WebRequest;
 use MediaWiki\SpecialPage\SpecialPage;
 use MediaWiki\Title\Title;
diff --git a/includes/specials/SpecialUnlockdb.php b/includes/specials/SpecialUnlockdb.php
index 36bdd1bc6f6..0c11af6212d 100644
--- a/includes/specials/SpecialUnlockdb.php
+++ b/includes/specials/SpecialUnlockdb.php
@@ -24,7 +24,7 @@
 namespace MediaWiki\Specials;
 
 use ErrorPageError;
-use HTMLForm;
+use MediaWiki\HTMLForm\HTMLForm;
 use MediaWiki\MainConfigNames;
 use MediaWiki\SpecialPage\FormSpecialPage;
 use MediaWiki\Status\Status;
diff --git a/includes/specials/SpecialUpload.php b/includes/specials/SpecialUpload.php
index 7a271edbad3..06516bdeb29 100644
--- a/includes/specials/SpecialUpload.php
+++ b/includes/specials/SpecialUpload.php
@@ -27,7 +27,6 @@ namespace MediaWiki\Specials;
 use BitmapHandler;
 use ChangeTags;
 use ErrorPageError;
-use HTMLForm;
 use ImageGalleryBase;
 use LocalFile;
 use LocalRepo;
@@ -35,6 +34,7 @@ use LogEventsList;
 use MediaWiki\Config\Config;
 use MediaWiki\HookContainer\HookRunner;
 use MediaWiki\Html\Html;
+use MediaWiki\HTMLForm\HTMLForm;
 use MediaWiki\MainConfigNames;
 use MediaWiki\MediaWikiServices;
 use MediaWiki\Request\FauxRequest;
diff --git a/includes/specials/SpecialUploadStash.php b/includes/specials/SpecialUploadStash.php
index 43f296776fd..cae0bb7bf65 100644
--- a/includes/specials/SpecialUploadStash.php
+++ b/includes/specials/SpecialUploadStash.php
@@ -24,10 +24,10 @@ namespace MediaWiki\Specials;
 
 use Exception;
 use File;
-use HTMLForm;
 use HttpError;
 use LocalRepo;
 use MediaWiki\Html\Html;
+use MediaWiki\HTMLForm\HTMLForm;
 use MediaWiki\Http\HttpRequestFactory;
 use MediaWiki\MainConfigNames;
 use MediaWiki\SpecialPage\UnlistedSpecialPage;
diff --git a/includes/specials/SpecialUserLogout.php b/includes/specials/SpecialUserLogout.php
index 6f7e5931edf..434824a74d4 100644
--- a/includes/specials/SpecialUserLogout.php
+++ b/includes/specials/SpecialUserLogout.php
@@ -24,7 +24,7 @@
 namespace MediaWiki\Specials;
 
 use ErrorPageError;
-use HTMLForm;
+use MediaWiki\HTMLForm\HTMLForm;
 use MediaWiki\Session\SessionManager;
 use MediaWiki\SpecialPage\FormSpecialPage;
 use MediaWiki\SpecialPage\SpecialPage;
diff --git a/includes/specials/SpecialWhatLinksHere.php b/includes/specials/SpecialWhatLinksHere.php
index 0f674c4f3c1..3c9bc7a5aa2 100644
--- a/includes/specials/SpecialWhatLinksHere.php
+++ b/includes/specials/SpecialWhatLinksHere.php
@@ -22,11 +22,11 @@
 
 namespace MediaWiki\Specials;
 
-use HTMLForm;
 use MediaWiki\Cache\LinkBatchFactory;
 use MediaWiki\Content\IContentHandlerFactory;
 use MediaWiki\Html\FormOptions;
 use MediaWiki\Html\Html;
+use MediaWiki\HTMLForm\HTMLForm;
 use MediaWiki\Linker\LinksMigration;
 use MediaWiki\MainConfigNames;
 use MediaWiki\Navigation\PagerNavigationBuilder;
diff --git a/includes/specials/SpecialWithoutInterwiki.php b/includes/specials/SpecialWithoutInterwiki.php
index 4bb6c6ab5c9..1e3be9138e5 100644
--- a/includes/specials/SpecialWithoutInterwiki.php
+++ b/includes/specials/SpecialWithoutInterwiki.php
@@ -24,8 +24,8 @@
 
 namespace MediaWiki\Specials;
 
-use HTMLForm;
 use MediaWiki\Cache\LinkBatchFactory;
+use MediaWiki\HTMLForm\HTMLForm;
 use MediaWiki\Languages\LanguageConverterFactory;
 use MediaWiki\SpecialPage\PageQueryPage;
 use MediaWiki\Title\NamespaceInfo;
diff --git a/includes/specials/formfields/EditWatchlistCheckboxSeriesField.php b/includes/specials/formfields/EditWatchlistCheckboxSeriesField.php
index 99b0f535804..5106d49a886 100644
--- a/includes/specials/formfields/EditWatchlistCheckboxSeriesField.php
+++ b/includes/specials/formfields/EditWatchlistCheckboxSeriesField.php
@@ -18,6 +18,9 @@
  * @file
  */
 
+use MediaWiki\HTMLForm\Field\HTMLMultiSelectField;
+use MediaWiki\HTMLForm\HTMLFormField;
+
 class EditWatchlistCheckboxSeriesField extends HTMLMultiSelectField {
 	/**
 	 * HTMLMultiSelectField throws validation errors if we get input data
diff --git a/includes/specials/formfields/Licenses.php b/includes/specials/formfields/Licenses.php
index b0a1fa53e4a..6f66630bc93 100644
--- a/includes/specials/formfields/Licenses.php
+++ b/includes/specials/formfields/Licenses.php
@@ -24,6 +24,7 @@
  */
 
 use MediaWiki\Html\Html;
+use MediaWiki\HTMLForm\HTMLFormField;
 use MediaWiki\MediaWikiServices;
 
 /**
diff --git a/includes/specials/forms/EditWatchlistNormalHTMLForm.php b/includes/specials/forms/EditWatchlistNormalHTMLForm.php
index 00e79b97064..d20b6caf9af 100644
--- a/includes/specials/forms/EditWatchlistNormalHTMLForm.php
+++ b/includes/specials/forms/EditWatchlistNormalHTMLForm.php
@@ -18,6 +18,8 @@
  * @file
  */
 
+use MediaWiki\HTMLForm\OOUIHTMLForm;
+
 /**
  * Extend OOUIHTMLForm purely so we can have a more sensible way of getting the section headers
  */
diff --git a/includes/specials/forms/PreferencesFormOOUI.php b/includes/specials/forms/PreferencesFormOOUI.php
index d870156274a..0c65e7e86ff 100644
--- a/includes/specials/forms/PreferencesFormOOUI.php
+++ b/includes/specials/forms/PreferencesFormOOUI.php
@@ -18,6 +18,10 @@
  * @file
  */
 
+use MediaWiki\HTMLForm\Field\HTMLCheckField;
+use MediaWiki\HTMLForm\Field\HTMLToggleSwitchField;
+use MediaWiki\HTMLForm\HTMLNestedFilterable;
+use MediaWiki\HTMLForm\OOUIHTMLForm;
 use MediaWiki\User\User;
 
 /**
diff --git a/includes/specials/pagers/CategoryPager.php b/includes/specials/pagers/CategoryPager.php
index b5e47ef5d09..5ae40cb1b77 100644
--- a/includes/specials/pagers/CategoryPager.php
+++ b/includes/specials/pagers/CategoryPager.php
@@ -21,10 +21,10 @@
 
 namespace MediaWiki\Pager;
 
-use HTMLForm;
 use MediaWiki\Cache\LinkBatchFactory;
 use MediaWiki\Context\IContextSource;
 use MediaWiki\Html\Html;
+use MediaWiki\HTMLForm\HTMLForm;
 use MediaWiki\Linker\LinkRenderer;
 use MediaWiki\Title\Title;
 use MediaWiki\Title\TitleValue;
diff --git a/includes/specials/pagers/ImageListPager.php b/includes/specials/pagers/ImageListPager.php
index 7ce35ec57f9..4004ff011e1 100644
--- a/includes/specials/pagers/ImageListPager.php
+++ b/includes/specials/pagers/ImageListPager.php
@@ -21,12 +21,12 @@
 
 namespace MediaWiki\Pager;
 
-use HTMLForm;
 use LocalRepo;
 use MediaWiki\CommentFormatter\CommentFormatter;
 use MediaWiki\CommentStore\CommentStore;
 use MediaWiki\Context\IContextSource;
 use MediaWiki\Html\Html;
+use MediaWiki\HTMLForm\HTMLForm;
 use MediaWiki\Linker\LinkRenderer;
 use MediaWiki\MainConfigNames;
 use MediaWiki\SpecialPage\SpecialPage;
diff --git a/includes/specials/pagers/UsersPager.php b/includes/specials/pagers/UsersPager.php
index 652f3b0ae98..242fbb68e41 100644
--- a/includes/specials/pagers/UsersPager.php
+++ b/includes/specials/pagers/UsersPager.php
@@ -25,7 +25,6 @@
 
 namespace MediaWiki\Pager;
 
-use HTMLForm;
 use HTMLHiddenField;
 use HTMLInfoField;
 use HTMLSelectField;
@@ -36,6 +35,7 @@ use MediaWiki\Context\IContextSource;
 use MediaWiki\HookContainer\HookContainer;
 use MediaWiki\HookContainer\HookRunner;
 use MediaWiki\Html\Html;
+use MediaWiki\HTMLForm\HTMLForm;
 use MediaWiki\Linker\Linker;
 use MediaWiki\MainConfigNames;
 use MediaWiki\Title\Title;
diff --git a/includes/user/Options/UserOptionsManager.php b/includes/user/Options/UserOptionsManager.php
index 4569f5f47c6..766fe2bb64e 100644
--- a/includes/user/Options/UserOptionsManager.php
+++ b/includes/user/Options/UserOptionsManager.php
@@ -22,7 +22,6 @@ namespace MediaWiki\User\Options;
 
 use DBAccessObjectUtils;
 use HTMLCheckMatrix;
-use HTMLFormField;
 use HTMLMultiSelectField;
 use IDBAccessObject;
 use InvalidArgumentException;
@@ -32,6 +31,7 @@ use MediaWiki\Config\ServiceOptions;
 use MediaWiki\Context\IContextSource;
 use MediaWiki\HookContainer\HookContainer;
 use MediaWiki\HookContainer\HookRunner;
+use MediaWiki\HTMLForm\HTMLFormField;
 use MediaWiki\Languages\LanguageConverterFactory;
 use MediaWiki\MainConfigNames;
 use MediaWiki\MediaWikiServices;
diff --git a/tests/phpunit/includes/htmlform/HTMLFormFieldTest.php b/tests/phpunit/includes/htmlform/HTMLFormFieldTest.php
index 66349a53852..2b62f1de92e 100644
--- a/tests/phpunit/includes/htmlform/HTMLFormFieldTest.php
+++ b/tests/phpunit/includes/htmlform/HTMLFormFieldTest.php
@@ -2,6 +2,9 @@
 
 use MediaWiki\Context\DerivativeContext;
 use MediaWiki\Context\RequestContext;
+use MediaWiki\HTMLForm\Field\HTMLFormFieldCloner;
+use MediaWiki\HTMLForm\HTMLForm;
+use MediaWiki\HTMLForm\HTMLFormField;
 use MediaWiki\Request\FauxRequest;
 use MediaWiki\Status\Status;
 use MediaWiki\Title\Title;
diff --git a/tests/phpunit/unit/includes/htmlform/HTMLCheckMatrixTest.php b/tests/phpunit/unit/includes/htmlform/HTMLCheckMatrixTest.php
index bf067da6b2e..007e2c6aee3 100644
--- a/tests/phpunit/unit/includes/htmlform/HTMLCheckMatrixTest.php
+++ b/tests/phpunit/unit/includes/htmlform/HTMLCheckMatrixTest.php
@@ -1,5 +1,10 @@
 <?php
 
+use MediaWiki\HTMLForm\Field\HTMLCheckMatrix;
+use MediaWiki\HTMLForm\HTMLForm;
+use MediaWiki\HTMLForm\HTMLFormField;
+use MediaWiki\HTMLForm\HTMLFormFieldRequiredOptionsException;
+
 /**
  * @covers HTMLCheckMatrix
  */