About a billion people that inherit the internet. But hey, at least they taught me better than my parents not to give two shits about what people say about you.
Although it's hard to really say they are characters. They're more like... faceless parasites.
As for fictional characters: Pretty much everyone from Final Fantasy 7, I must say. They're the reason I stopped playing the game. And the deagle from Counter-Strike. Again, the reason I stopped playing.
PS: Don't even ask, that gun IS a character. A malicious evil bastard risen from hell to make my Online-FPS-gaming life turn to shit. Until Left 4 Dead came - haha >

late victory.