​From Wikipedia, the free encyclopedia.   Mars Callahan (born 1971) is an American actor, director, producer and writer. He is known, among other things, for the movie Poolhall Junkies where he served as director, actor and screenwriter. At the age of eleven Callahan toured with a children's musical group through thirty-seven states. At fifteen he received his first acting role in the television series The Wonder Years. After honing his acting skills in television he tried for the big screen ...