The goal here is simple. The following characters have been summoned for the task of antagonizing their respective archenemy to the point of eliciting a strong emotional response and/or possible violence. The winner would be the one who makes their respective foe "snap" the most, possibly compromising their values and code of conduct. They're allowed to do anything in character with their knowledge and resources, short of killing their enemy (who can attempt to foil them normally if/when they catch wind of their enemy).
Dr. Doom
Red Skull
Magneto (assume this is "classic" Mags and Xavier is still alive)
Loki
Norman Osborn
Sabertooth
Mandarin
Joker
Lex Luthor
Ares
Black Adam
Sinestro
Professor Zoom
Black Manta
Obviously, there are tons of troll-tastic villains out there, so by all means, feel free to argue for someone you feel deserves the top nod.
Actually, I think Joker is a great troll when it comes to Batman. Ultimately, Batman will never cave in all the way, but Joker has pushed him incredibly close before. Hell, he didn't even "kill" Thomas Elliot, and Batman snapped to the point where he would have killed him had it not been for Gordon being there.
That's why I said not Joker. He's bar none the greatest troll, but in the spirit of the thread? If he hasn't gotten Batman to lose discipline by now it'll never happen lol. Says a helluva lot about Bats though. Not to lose discipline and cave in to the worst human emotions I mean.
Well, he did succeed in making Batman willingly and gladly break "his one rule". It's just so happened that Bats' allies happened to be there to stop him.
Ares or Sabertooth. They troll hard and their trollees are likely to fall for it. A crazy amazon beetch and an animal with killer instincts don't stand a chance.
Thanos doesn't really have an "archenemy" (well, Mar-Vell I suppose, and to a lesser extent, Warlock) and doesn't really make plots solely for their ruin/destruction/humiliation.