Martin Eugene Mull (born in 1943) is an American actor of many films and TV-shows. Mull is also a painter, comedian, and recording artist. His role on Mary Hartman made him a famous actor. He is also widely known for the roles of Colonel Mustard in the 1985 film Clue, Willard Kraft on Sabrina, Leon Carp on Roseanne, the Teenage Witch, and Russell the pharmacist on the hit sitcom Two and a Half Men.

Mull's first well known acting role was as Garth Gimble in the 1976 television nighttime absurdist soap opera Mary Hartman, Mary Hartman. This led to work in the spin-off comedy talk shows Fernwood 2 Night (1977) and America 2-Night (1978), in which he played talk show host Barth Gimble (Garth Gimble's twin brother), opposite Fred Willard, as sidekick Jerry Hubbard. In 1979, Mull appeared in the Taxi episode Hollywood Calling.

He created, wrote for and starred in the short-lived 1984 CBS sitcom Domestic Life, with Megan Follows playing his teenaged daughter. In one episode of The Golden Girls, he played a hippie who was afraid of the outside world. He had a long-running role as Leon Carp, Roseanne Conner's gay boss (and later business partner) on the TV series Roseanne.

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