7. Jack Nicholson - The Godfather
Back in the 1970s, Jack Nicholson was up for the iconic role of Michael Corleone in The Godfather, a character that has been immortalized by Al Pacino. The reason that he passed on the part was because at the time, he thought that only Italians should play Italians. While I can appreciate the desire for authenticity, I find this somewhat spurious logic -- surely the point of acting is to pretend to be something you're not? Oh well. Jack Nicholson has had more than enough career-defining roles to make up for missing out on The Godfather. And while Jack Nicholson, especially at his creative peak in the 70s, could be well trusted with pretty much any character, I'd be more than a little sad if I never got to see Al Pacino's version of the character.