Which formerly lovable hero became way too much of a jerk?S

It never fails: When a hero has been around too long, or the writers run out of ideas, they start playing up the hero's "dark side." And often, that means your favorite champion becomes kind of a dick. Who's your least favorite example of a hero who became so mean, or so antiheroic, that they weren't likable any more?

Please include a picture of your good guy gone annoying, so we can all sympathize!