From Wikipedia, the free encyclopedia. Greydon Clark (b. February 7, 1943) is an American film writer, director, producer, and actor. His career spans several decades and genres, although the majority of his work has been low-budget productions in the action/horror genres. His most recent work was writing and directing the 1998 science fiction movie Stargames, starring Tony Curtis. Between 1969 and 1989, Clark acted in a series of action/horror films, including Satan's Sadists, Hell's Bloody D...