John McClane (Die Hard)
It was said that Arnold Schwarzenegger was the first to receive an offer to play policeman McClane, and this movie was supposed to be the sequel to his 1985 action film Commando. But Iron Arnie rejected this offer for ethical reasons: the main negative characters were terrorists with a German accent, and Arnie had this accent as well.
Sylvester Stallone, Harrison Ford, and Don Johnson were the other candidates. But Bruce Willis, an actor only known at the time for his comedy roles, got the part.