En voici une :

<?php
/*
 * Plugin Name: Modify Blog Post Titles
 * Author: Your Name
 * Author URI: Your URL
 * Description: Creating a Simple WordPress Plugin to Modify Blog Post Titles
 * */

/* Changing the title of a blog post */
function change_the_title( $title ) {
	return "The title of " . $title . "has been changed";
}

add_filter( 'the_title', 'change_the_title' );

Il modifie également les titres dans la zone d'administration. 

Si vous ne souhaitez pas modifier le titre dans la zone d'administration, utilisez ceci : 

/*
 * Plugin Name: Modify Blog Post Titles
 * Author: Your Name
 * Author URI: Your URL
 * Description: Creating a Simple WordPress Plugin to Modify Blog Post Titles
 * */

/* Changing the title of a blog post */
function change_the_title( $title ) {
	if ( is_admin() ) {
		return $title;
	}
	return "The title of " . $title . "has been changed";
}

add_filter( 'the_title', 'change_the_title' );