March 11th, 2013
Reserve words so that new users cannot register with a forbidden username. You can reserve usernames by specifying two lists of forbidden words. The first is a list of words that cannot be used as new usernames on the site. The second is a list of words that cannot appear anywhere within a username.
Configuration options include custom error messages and an option that allows administrators to override the reserved username restrictions when creating new accounts.
Ultania Reserved Usernames is a Joomla! plugin of type User.