Which character can you just not stand to even watch if they're in an episode?

For me, it's Harry Crane. Ugh. I can't even pinpoint exactly why I don't like him. A combination of many traits I suppose. But I just tune out and ignore him if he's in a scene so I can give my mind some peace from constantly hating on him. With some characters, while I don't really like them as people, I still enjoy to watch them. Not with Harry.

So who do YOU not like to watch at all? Who makes you sigh and groan every time they come on screen, and why?