GTA Wiki's username policy is a policy regarding permissible usernames.
What is disallowed
Usernames may not be misleading, offensive, promotional, or disruptive.
Misleading usernames may take the form of impersonating a real life person, claiming affiliation with an organization, or claiming a position of authority on this or any other wiki.
Usernames containing profanity, either obscured or blatant, are disallowed, as are usernames intended to "attack".
Usernames intended to advertise something.
Any username not covered by the above criteria but still disruptive.
As a general rule of thumb, editors blocked for usernames should have the policy politely explained to them and have it requested that they register a different name. They should be blocked with talk page access and account creation enabled.
In the case of usernames used deliberately to attack, disrupt or troll, the blocking sysop may use his or her judgment in whether to recommend reregistering with a different name or simply blocking indefinitely.