Clyde Gash wrote:Charles Laughton
You could argue that he DID fulfill his potential in a single film. It's as great as anything. I'd say the same about Cimino...his great early films likely fulfilled any promise he could have been said to have.
The suggestion of Brando is a good one, as One-Eyed Jacks" is kind of an unfinished masterwork. He clearly didn't live up to his potential as a director.
Someone mentioned Guy Ritchie, but I'll toss in Michael Ritchie. His early films made you think that he might have a great one in him - but it never fully materialized.