Dexter. Maybe not slapped around, but I'd love to see the last season or two has him going to prison. Yeah, he kills serial killers, but he's also tampered with evidence on numerous times and killed people that could have just been locked up. Whether that would have solved anything, I don't know, but he started by going after the ones that got away because of a bad system. More and more, he goes after guys that he could simply help gather evidence against and ensure they go away forever.
He's a great character, but it'd be REALLY interesting to do a prison season. Everyone finding out the truth about him would pretty much be the end of the show, but you could still do one more with him in prison or something.