McHattie was born in Antigonish, Nova Scotia, on February 3, 1946 (the year of his birth has also been cited as 1945, 1947, and 1948). An alumnus of the American Academy of Dramatic Arts, he has appeared in many films and television shows including Star Trek: Deep Space Nine, Star Trek: Enterprise, Highlander: The Series, and American Playhouse's Life Under Water (1989). His roles include 300, A History of Violence, The Fountain, Secretary, Shoot 'Em Up, Life with Billy, One Dead Indian, Beverly Hills Cop III
In Canada, he appeared in Canada: A People's History as Canadian hero Major-General Sir Isaac Brock, and in The Rocket as coach Dick Irvin.