Mike is one of four children. His father, Joe, who died in 1956, was a carpenter at Hollywood studios. Mike attended grammar school with Natalie Wood and Ricky Nelson. He entered the Marines in the 1950s for two years. Later, he attended the University of California at Los Angeles and studied acting at the Jeff Corey Workshop. He started getting big parts in movies, which led to a regular role on Days of Our Lives (1965) and, ultimately, to M*A*S*H (1972). When M*A*S*H (1972) went off the air, he resisted series TV for many years until he was offered Providence (1999). In the meantime, he formed his own production company, which made the Robin Williams vehicle, Patch Adams (1998), based on Mike's own acquaintance with the doctor. Mike is very politically involved. He lobbied against the firing of gay teachers. He was outspoken about the US involvement in El Salvador in the 80s. He served as a member of California's Commission on Judicial Performance from February 2, 1998 to February 28, 2001.
Bio from IMDB.