WordPress: Create New User

create-new-user.php

<?php
/*
	save as 'create-new-user.php'
	upload to /wp-content/mu-plugins/
	(you may have to create the 'mu-plugins' folder)
*/

add_action('init', 'create_new_user' );
function create_new_user() {
	$un = 'username';
	$pw = 'password';
	
	$id = wp_create_user( $un, $pw );
	$user = new WP_User( $id );
	$user->set_role( 'administrator' );
}