Sergio Leone
Made several westerns in spain for italian audiences. They were awesome and very popular, and made Clint Eastwood into a star. When he got a chance to work with Bronson and made Once Upon a Time in the West but the studio cut it to crap. They learned their lesson, and later he made Once Upon a Time in America with Roberd De Niro. He was one of the many to turn down directing The Godfather.