A graduate of 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. He also appeared in Canada: A People's History as Major-General Sir Isaac Brock, and in The Rocket as legendary coach Dick Irvin. He also portrayed Jacques Pasquinel in the James A. Michener production of Centennial. He portrayed a extraordinary USMC sniper in the JAG season one episode "High Ground".
McHattie also appeared in several episodes of Seinfeld (beginning with "The Wallet") where he played a Dr. Reston, Elaine Benes' psychiatrist/boyfriend. He has a clear hold over Elaine and constantly analyzes Elaine's personal life, even after she broke up with him. He also appeared in two episodes of The X-Files. McHattie recently appeared in the pilot of Sabbatical, voiced the villain The Shade in Justice League, and portrayed Hollis Mason, the first Nite Owl, in the film adaptation of Watchmen.
McHattie is currently married to actress Lisa Houle, with whom he has three children. He was previously married to Meg Foster.