Mark Holton is an American actor who is best known for playing the role of John Wayne Gacy in the 2003 biographical film, Gacy. Born in 1958, the Oklahoma City, Ok. native was first seen by a nationwide audience when he played a clown on the television series, Webster in 1984. After his debut, Holton moved to film, where he would play the antagonist in the 1985 hit comedy, Pee Wee's Big Adventure. His fame continued to rise as a he also played the role of Chubb in both versions of the Teen Wolf movie series in 1985 and 1987. At 45, Holton earned his first starring role when he was selected to play Gacy in the movie of the same name. Though the film earned mixed reviews, it served as the actor's coming out party after years of supporting roles. On the small screen, Holton has never became an official cast member for any particular show, however he did act in many hit shows in the 1990s and 2000s. Most notable among his appearances included stints on Star Trek: Deep Space Nine, NCIS and NYPD Blue.