Seth MacFarlane. I think he's an unfunny hack that relies far too much on shock value for laughs. But that isn't what bothers me the most about him, as I admit his shows will occasionally get a laugh out of me, if I'm in the right mood. I happen to side with him on a lot of issues, but any time he tries to incorporate these issues into his work, I want to disagree with him on principle, because he does it with such a lack of subtlety, and always demonizes those who oppose him. He also seems to this impenetrable air of smugness every time I see him on live action TV that makes me just want to punch him in the face.
Pardon the essay. I used to share an apartment with someone who was obsessed with Family Guy. I think it's changed me permanently.