Rosh from Jedi Knight: Jedi Academy. Fucking hate that moron.
"HAY! CAN I SEE YOUR LIGHTSABER?" "WANNA BE FRIENDS?" "I'M A DICK! I'M GONNA FUCK UP YOUR JEDI TRAILS AND THEN GET REALLY BUTTHURT WHEN YOU STILL PASS AND GO EVIL FOR NO GOOD REASON AT ALL."
Now I normally pick the "good" path when I play a game where you can morally choose what your character does, at least the first time around. But when I was given the opportunity to kill this guy, you bet your ass I took it.