I am a sucker for badasses with awesome hair. A character who will look at you in such a way that makes you say to them, "I am going to kick my own ass, to save you the trouble, because you look very busy and I don't want your hair to get mussed while you remove my intestines through my nose. Yeah, I'll just take care of this myself. Carry on."
I also like it when these characters are the good guys. :D

I like characters who have mental illnesses/disorders that make them unpredictable, particularly if they think on a totally different level than everyone else. They tend to keep my interest. I especially like it if they have a better understanding than the normal people of the way things are.

Skullbie

wagh skullbie you like mio??!! Yui is way better!! she's so cutee. (*never ending girl's life...* )

my fave characters are morally ambiguous/wrong but have some sort of identifiable reason for being like that. Bonus points if they're stoic and stalwart.

examples:
Javert (Les Miserables)
Rorschach (Watchmen)
Light (Deathnote)
Perry Smith (from In Cold Blood... this one might make me sound like a crazy person since the book was nonfiction about a murderer, but I'm not, like, justifying his actions!! I just liked the way he was presented in the book.)
Mr. Rochester (from Jane Eyre... finally someone who's not like a crazy murderer! lol SIGH OF RELIEF)