I find any kind of fan who cannot except when something isn't that great, incredibly annoying. The kind that will give something a 10/10 just because, not because it was actually worth it.
Twilight fans who try to tell me about the deeper meaning in the stories. I know stories with meanings, and I still can't find anything deep in Twilight. Especially the movies, which I will continue to watch as more of an acceptable substitute for porn for women than anything else.
But then again I imagine I must be annoying to a lot of people.
1. I'm a devout Whedonite. Very defensive. Will rarely concede that anything he has ever done was less than perfect

(which totally makes me a hypocrite)
2. I am a Superman fan, post crisis era. Usually end up in arguements with people who think Clark Kent is the disguise. Do get quite angry about it.
3. I'm one of those Smallville fans who sometimes only watches it because I love to complain about it.