They say good casting is 90% of a film's potential success. Finding the right actor for the role is always a challenge, but what about when more than one actor is going to inhabit the same part—be it at a different age, with a different face, or in a somewhat altered reality? Here is a look at 10 films that feature the same role played handily by different actors. One more we might mention is the upcoming Looper, opening September 28,  in which Joseph Gordon-Levitt and Bruce Willis inhabit the same skin. Consider this your role-sharing primer.