It's very easy to cite great actors in jaw-droppingly terrible movies. Hell, pretty much EVERY actor with a resume of reasonable length has a terrible dog on there somewhere. As Michael Caine said of Jaws IV, "I haven't seen the movie, but I've heard that it's terrible. I have seen the house that it built, and it is fantastic."

But here's a twist; what is the worst actor, or worst performance, ever, in a truly great movie?

Note that you cannot yourself think the movie was terrible. Otherwise the entire thread will be people saying "Titanic won the Oscar but Leonardo DiCaprio is the suxxor that movie sucked." No. If you legitimately believe Titanic was just an awesome movie and deserved the Oscar, but Billy Zane sucked, fair answer. You have to cite performances from movies you think were truly great.

We'll have two categories:
- Worst Performance By An Actor/Actress In A Truly Great Movie
- Performance By The Worst Overall Actor/Actress In a Great Movie, Given Their Entire Body of Work, But In This Movie He/She Was Not As Terrible As They Usually Are