
Michael Leonard Ontkean (born January 24, 1946) is a Canadian retired actor. Born and raised in Vancouver, British Columbia, Ontkean relocated to the United States to attend the University of New Hampshire on a hockey scholarship before pursuing a career in acting in the early 1970s.
He initially came to prominence portraying Officer Willie Gillis on the crime drama series The Rookies from 1972 to 1974, followed by lead roles in the hockey sports comedy film Slap Shot (1977) and the romantic comedy Willie & Phil (1980). In 1982, he had a starring role opposite Harry Hamlin and Kate Jackson in the drama Making Love, in which he portrayed a married man who comes to terms with his homosexuality. Ontkean continued to appear in films, such as Clara's Heart (1988) and Postcards from the Edge (1990) before being cast as Sheriff Harry S. Truman on David Lynch's Twin Peaks (1990–1991), the role for which he is best known.

Slap Shot
1977 · as Ned Braden

The Descendants
2011 · as Cousin Milo

Twin Peaks
1989 · as Sheriff Harry S. Truman

Postcards from the Edge
1990 · as Robert Munch

Twin Peaks: The Missing Pieces
2014 · as Sheriff Harry S. Truman

The Allnighter
1987 · as Mickey Leroi

Maid to Order
1987 · as Nick McGuire

Making Love
1982 · as Zach

Clara's Heart
1988 · as Bill Hart

The Blood of Others
1984 · as Jean

Nico the Unicorn
1998 · as Tom Gentry

Bye Bye Blues
1989 · as Teddy Cooper

Mrs. Ashboro's Cat
2003 · as Wes Merritt

Street Justice
1987 · as Curt Flynn

Pickup on 101
1972 · as Chuck

Just a Little Harmless Sex
1999 · as Jeff

Green Sails
2000 · as John Scott

Legacy of Lies
1992