Board Thread:Support Requests - Community Management/@comment-24155515-20140222012155/@comment-366087-20140222032823

One of the default options for Blocks is "Unacceptable Username".

In addition to obvious TOU violating words, terms, and phrases such as Kamikaze quoted being passed off as "a name", each wiki has the right to determine what is Unacceptable to their local communities. By taking into consideration such factors as Nature of Wiki and Target Demographic of the Topic, Usernames (and behavior) which are deemed acceptable on other wikis can also be considered as unacceptable on any single (or more) wiki.

You might also give them the option to change their username, or make an alternate account specific for your wiki. Which is an acceptable purpose for a "sock".

Act as you believe to be in the best interest of your local community. If the recipient feels it to be unwarranted they can appeal to Special:Contact. However, Staff rarely intervenes with local affairs.