6. James Dean - Giant
Warner BrosDespite the tremendous impact James Dean has had on popular culture, the actor only appeared in three films before his untimely death at the age of 24. After starring in Rebel Without a Cause, the ultimate film about teenage rebellion, and receiving acclaim for his performance as Jim Stark, he was concerned that he would have a hard time being taken seriously in adult roles. So he took on the challenge of playing Jett Rink in Giant, which required him, among other things, to convincing portray a character over a period of many years. He takes Rink from a young man working on a ranch in Texas to a bitter but wealthy alcoholic pining over a woman he can never have. James Dean was killed in a car crash before film could be released, leading actor Nick Adams to do a small amount of voice-over dubbing to finish the film. He received posthumous Oscar nominations for Giant and East of Eden, another film that Dean starred in (and the only one that was actually released during his lifetime). The fact that Dean died so young cemented his iconic status in popular culture -- he didn't live long enough to make a bad movie, or for audiences to get learn enough about him to break down his mysterious image.