In Hollywood, one good role can proper your entire career. But, there were a few artists that turned down the biggest roles in their entire career. The people replacing them are now the most prestigious actors in Hollywood and made enough buck that they probably don't have to work anymore. I think it's an understatement to say that these 15 actors regret their choice.
George Lucas actually wanted Christopher Walken in the new Star Wars movie. But, he refused and Harrison Ford was offered the role.