I think it actually is legal. There was a story about the guy who owns YTMND.com who also owned DustinDiamond.com (Screech from saved by the bell). He was sued over it by Diamond, but still won in court...he still owns the domain name.
If it's a fan site, I doubt that you will have any problems. Also, I don't really see what they have to sue about as anyone can have a celebrity's name.
If: a) the celebrity has established trademark rights to his/her name, and b) the owner with their domain name-sake infringes it, then the celebrity might sue under applicable laws and/or policies. Look up the Julia Roberts and Bruce Springsteen cases for examples that went both ways.
Hm...That doesn't seem fair as a non-celebrity with a celebrity's name has just as much right to his/her name as the celebrity does.
Julia Roberts and Bruce Springsteen go both ways? I always had my doubts seeing the way Bruce french kissed Clarence Clemons before each concert. http://farm4.static.flickr.com/3651/3632375218_85b3dcbd24.jpg
Well, does it seem fair if a non-celebrity registers a celebrity's domain name to make money off that celebrity's name, especially if that celebrity's commercial success arose from his/her hard work? It's debatable who has as much "right" towards a domain name between the celebrity and its current registrant, but... there's enough decisions abound to indicate one can't use that to make money off that celebrity's trademark right if any. Of course, that's if the celebrity uses his name as a trademark. Not all of them do that, anyway. And LOL at browntwn.