Born as Allan See in Mount Kisco, New York, he grew up in Pleasantville and studied acting at Ithaca College, graduating in 1952. After serving in the Air Force, he moved to New York City and worked at Radio City Music Hall while looking for acting work. At about this time he changed his name, drawing "Gavin" from a cerebral palsy victim in a TV drama, and "MacLeod" from his Ithaca drama coach Beatrice MacLeod.
His first movie appearance was in I Want To Live, a 1958 prison drama. He also appeared as the villain in TV shows of the late 1950s and early 1960s. His first regular TV role came in 1962 as Joseph "Happy" Haines on McHale's Navy.
MacLeod's role on Mary Tyler Moore won him lasting fame, and two Golden Globe nominations, followed by another three nominations for his Love Boat work.
Along with his wife Patti, he wrote about struggles with divorce and alcoholism in Back On Course: The Remarkable Story of a Divorce That Ended in Remarriage.
Filmography
Television