diff --git a/src/wp-admin/includes/class-wp-list-table.php b/src/wp-admin/includes/class-wp-list-table.php
index 0b20f6be0c99..8ccd02998fd4 100644
--- a/src/wp-admin/includes/class-wp-list-table.php
+++ b/src/wp-admin/includes/class-wp-list-table.php
@@ -419,12 +419,29 @@ public function views() {
 	}
 
 	/**
-	 * Gets the list of bulk actions available on this table.
+	 * Retrieves the list of bulk actions available for this table.
 	 *
-	 * The format is an associative array:
-	 * - `'option_name' => 'option_title'`
+	 * The format is an associative array where each element represents either a top level option value and label, or
+	 * an array representing an optgroup and its options.
+	 *
+	 * For a standard option, the array element key is the field value and the array element value is the field label.
+	 *
+	 * For an optgroup, the array element key is the label and the array element value is an associative array of
+	 * options as above.
+	 *
+	 * Example:
+	 *
+	 *     [
+	 *         'edit'         => 'Edit',
+	 *         'delete'       => 'Delete',
+	 *         'Change State' => [
+	 *             'feature' => 'Featured',
+	 *             'sale'    => 'On Sale',
+	 *         ]
+	 *     ]
 	 *
 	 * @since 3.1.0
+	 * @since 5.6.0 A bulk action can now contain an array of options in order to create an optgroup.
 	 *
 	 * @return array
 	 */
@@ -445,14 +462,15 @@ protected function bulk_actions( $which = '' ) {
 			$this->_actions = $this->get_bulk_actions();
 
 			/**
-			 * Filters the list table bulk actions drop-down.
+			 * Filters the items in the bulk actions menu of the list table.
 			 *
 			 * The dynamic portion of the hook name, `$this->screen->id`, refers
-			 * to the ID of the current screen, usually a string.
+			 * to the ID of the current screen.
 			 *
 			 * @since 3.1.0
+			 * @since 5.6.0 A bulk action can now contain an array of options in order to create an optgroup.
 			 *
-			 * @param string[] $actions An array of the available bulk actions.
+			 * @param array $actions An array of the available bulk actions.
 			 */
 			$this->_actions = apply_filters( "bulk_actions-{$this->screen->id}", $this->_actions ); // phpcs:ignore WordPress.NamingConventions.ValidHookName.UseUnderscores
 
@@ -469,10 +487,21 @@ protected function bulk_actions( $which = '' ) {
 		echo '<select name="action' . $two . '" id="bulk-action-selector-' . esc_attr( $which ) . "\">\n";
 		echo '<option value="-1">' . __( 'Bulk actions' ) . "</option>\n";
 
-		foreach ( $this->_actions as $name => $title ) {
-			$class = 'edit' === $name ? ' class="hide-if-no-js"' : '';
+		foreach ( $this->_actions as $key => $value ) {
+			if ( is_array( $value ) ) {
+				echo "\t" . '<optgroup label="' . esc_attr( $key ) . '">' . "\n";
 
-			echo "\t" . '<option value="' . $name . '"' . $class . '>' . $title . "</option>\n";
+				foreach ( $value as $name => $title ) {
+					$class = ( 'edit' === $name ) ? ' class="hide-if-no-js"' : '';
+
+					echo "\t\t" . '<option value="' . esc_attr( $name ) . '"' . $class . '>' . $title . "</option>\n";
+				}
+				echo "\t" . "</optgroup>\n";
+			} else {
+				$class = ( 'edit' === $key ) ? ' class="hide-if-no-js"' : '';
+
+				echo "\t" . '<option value="' . esc_attr( $key ) . '"' . $class . '>' . $value . "</option>\n";
+			}
 		}
 
 		echo "</select>\n";
diff --git a/src/wp-admin/includes/class-wp-privacy-requests-table.php b/src/wp-admin/includes/class-wp-privacy-requests-table.php
index c75edcf2c07c..d2772bd60a8a 100644
--- a/src/wp-admin/includes/class-wp-privacy-requests-table.php
+++ b/src/wp-admin/includes/class-wp-privacy-requests-table.php
@@ -206,7 +206,7 @@ protected function get_views() {
 	 *
 	 * @since 4.9.6
 	 *
-	 * @return string[] Array of bulk action labels keyed by their action.
+	 * @return array Array of bulk action labels keyed by their action.
 	 */
 	protected function get_bulk_actions() {
 		return array(
diff --git a/src/wp-admin/includes/class-wp-users-list-table.php b/src/wp-admin/includes/class-wp-users-list-table.php
index ae5223884477..42cf19f5f887 100644
--- a/src/wp-admin/includes/class-wp-users-list-table.php
+++ b/src/wp-admin/includes/class-wp-users-list-table.php
@@ -259,7 +259,7 @@ protected function get_views() {
 	 *
 	 * @since 3.1.0
 	 *
-	 * @return string[] Array of bulk action labels keyed by their action.
+	 * @return array Array of bulk action labels keyed by their action.
 	 */
 	protected function get_bulk_actions() {
 		$actions = array();
diff --git a/tests/phpunit/tests/admin/includesListTable.php b/tests/phpunit/tests/admin/includesListTable.php
index a6b77af5b8d4..22e504537245 100644
--- a/tests/phpunit/tests/admin/includesListTable.php
+++ b/tests/phpunit/tests/admin/includesListTable.php
@@ -352,6 +352,42 @@ public function test_empty_trash_button_should_not_be_shown_if_there_are_no_comm
 		$this->assertNotContains( 'id="delete_all"', $output );
 	}
 
+	/**
+	 * @ticket 19278
+	 */
+	public function test_bulk_action_menu_supports_options_and_optgroups() {
+		$table = _get_list_table( 'WP_Comments_List_Table', array( 'screen' => 'edit-comments' ) );
+
+		add_filter(
+			'bulk_actions-edit-comments',
+			function() {
+				return array(
+					'delete'       => 'Delete',
+					'Change State' => array(
+						'feature' => 'Featured',
+						'sale'    => 'On Sale',
+					),
+				);
+			}
+		);
+
+		ob_start();
+		$table->bulk_actions();
+		$output = ob_get_clean();
+
+		$this->assertContains(
+			<<<'OPTIONS'
+<option value="delete">Delete</option>
+	<optgroup label="Change State">
+		<option value="feature">Featured</option>
+		<option value="sale">On Sale</option>
+	</optgroup>
+OPTIONS
+			,
+			$output
+		);
+	}
+
 	/**
 	 * @ticket 45089
 	 */