Board Thread:Support Requests - Community Management/@comment-5079138-20121219142610/@comment-168424-20121222071025

If your wiki is big enough and there is overwhelming wiki community support for having a custom domain name, Wikia might allow you to have one and they will pay for and maintain it. WoWWiki is not the only wiki that Wikia does this for, I think. Lyricwiki.com works for lyrics.wikia.com as well. Of course they are HUGE wiki and they may have come from a similar situation as WoWWiki (aka were large and hosted elsewhere before moving to Wikia).

As Randomtime said, you can register a domain that points to your *.wikia.com address, but you probably want to coordinate it with Wikia.