I don't really hate any actors particularly, I generally just tend to be irritated by certain people. If I HAD to pick under pain of tickling torture, I'd have to say Kirsten Stewart and Michael Cera. For me, their existence alone is proof that there is no God. I don't really hate them per se, just find them incredibly annoying to the point of atheism.
Not really actors but on the topic of people I used to/actively do hate:
I used to find my arm instinctively pulling itself into a position to launch a punch every time I saw Professor Brian Cox on T.V., but since he's toned down being himself a bit, I can tolerate him a bit more these days.
But the only person I can say I genuinely despise: Michael McIntyre. He is just such a goddamned fucking smug ****! I'd beat him to death, but I could just see that as I'm repeatedly punching him in the face shouting "DIE FUCKWAD, DIE!!!!" he'd just keep goddamned smiling that arrogant prickish overly middle class smile and laughing he's supposedly quirky, over chirpy laugh and I'd have to keep punching his face even after he's dead just to get rid of that fucking smile and even then that wouldn't be enough and I'd have to......
Okay, sorry. Got a little carried away there.
But yeah, Kirsten Stewart and Micheal Cera, if I had to choose.
[sub]God, I hate Michael McIntyre...[/sub]