Can you think of any movies that were just badly cast? That made you think, “Whose idea was it to put him (or her) in THAT role?”
I can think of one movie right away…Bram Stoker's Dracula. If you read Alex's excellent reivew and the comments that followed, you know that we differ on some things about this film. But one thing we agreed on was that Keanu Reeves was AWFUL in it. I myself thought Winona Ryder was pretty bad, too (I think Alex had a higher opinion of her than I did), but Reeves delivered one of the worst performaces I have ever seen.
I would also say that to some degree, the Harry Potter movies could have been better cast. Not the kids–they were perfect, and if they didn't really learn to act until the 3rd movie, that's down to the directors. But Alan Rickman, Gary Oldman, David Thewliss, and the two actors who had a few moments as Harry's parents…brilliant actors on their own merits, but FAR too old for these roles. And there is like 20 years' difference between Thewliss and Rickman, and they're supposed to be in the same class!
And I never could get into Michael Gambon as Dumbledore.
Still, at least they didn't cast Keanu Reeves…