Darren Aronofsky.
I had heard a lot about his previous movies, and had been interested in seeing them. Then I saw Noah in theaters and developed an instant dislike for him and his works, to the point I will never see one of his films again.
On a somewhat different note- I like Zack Snyder. I liked his DC movies. And by all accounts, he really is a nice person who gets along with almost everyone. But I swear, the die-hard Snyder fans on Twitter are starting to make me develop an irrational hatred of the man.
For what it's worth, I've heard that Heaven's Gate got a bad rap back in the day, and that people now consider it a good film.