How would certain movies turn out if the original chosen actor played the role?

O.J. Simpson as The Terminator (it would have been really awkward about a decade down the line) Will Smith as Neo (it could have worked, I would have preferred him in the role instead of no-act Keanu Reeves) Bill Murray as Batman (I know Bill is pretty much a god at this point, but I don't see how anyone thought this was a good idea) Leonardo DiCaprio as Patrick Bateman in American Psycho (Well, given the fact that American Psycho is my favorite Christian Bale performance, I'm glad Leo didn't get the role. Bale completely nails that character.)