Terrance Quinn, professionally known as Terry O'Quinn, is an American actor born on July 15, 1952, in War Memorial Hospital, Sault Ste. Marie, Michigan.
He is one of 11 siblings and grew up in nearby Newberry, Michigan, with Irish and English descent and a Roman Catholic upbringing.
O'Quinn attended Central Michigan University and the University of Iowa, changing his surname from Quinn to O'Quinn due to another actor with the same name.
He began acting in the 1970s, performing at Center Stage in Baltimore and appearing in his first film, Heaven's Gate.
O'Quinn also wrote and directed the musical Orchestrina during his time at Central Michigan University, where he was roommates with actor Brad Slaight.
He has appeared in numerous feature films, including Silver Bullet, Tombstone, Young Guns, Blind Fury, and The Rocketeer, as well as the Canadian horror movie Pin.
O'Quinn's early television roles include guest appearances on Miami Vice, Moonlighting, Star Trek: The Next Generation, The Twilight Zone, and Homicide: Life on the Street, as well as recurring roles on Earth 2 and JAG.
He made guest appearances in The X-Files and Harsh Realm, and held the role of Peter Watts in the television series Millennium, which ran for three seasons from 1996 to 1999.
O'Quinn holds the distinction of having played four different characters within the extended X-Files/Millennium continuum.
He has also hosted Mysteries of The Missing on The Science Channel.
O'Quinn played the title role in The Stepfather (1987) and Stepfather II: Make Room for Daddy (1989),and John Locke on the TV series Lost (2004).