O'Quinn began acting in the 1970s in films such as Tombstone and ''Heaven's Gate. His early television roles included guest appearances in Earth 2, Moonlighting, Star Trek: The Next Generation, and JAG''. Around 1995, O'Quinn began a series of guest appearances around shows by "The X-Files" producer Chris Carter. Additionally to "The X-Files," Carter cast his friend O'Quinn in the TV series Millennium and Harsh Realm as well as in the X-Files moving-picture show Fight the Future.

Fallowing the 2002 appearance on Alias, O'Quinn became a preferred of eventually an additional TV producer, this time J.J. Abrams. Resulting the seven-episode guest dog on The West Wing in 2003 and 2004, O'Quinn got a call for from either Abrams indicating that the producer wanted to cast him (while forgoing any audition required) around his freshly television drama Misused, all about the class actiin of humans stranded on the mysterious island when the plane crash. A mystery - conspiracy theory series proved an immediate profits by using viewers, & O'Quinn's character - a island's prophet of sorts - is a fan preferred. Within July 2005, O'Quinn received an Emmy nominatiin for best supporting actor inside the drama for his operate when John Locke on Wasted.

When of 2005 O'Quinn has been married to his married woman, Lori, for Twenty-five years. Virtually all of that period it sleep in Finksburg, Maryland, but after Misplaced began airing a few decided to watch a case of O'Quinn's co-stars & move to Hawaii, where a series is shot.

O'Quinn & his married woman come a parents to deuce grown sons, world health organization survive on the West Coast of the United States.

Selected Filmography
Lost (2004) TV Series .... John Locke Old School (2003) ... when Goldberg (uncredited) Alias (2002-2003) ... when F.B.We. Asst. Director Kendall Harsh Realm (1999) ... when General Omar Santiago The X-Files: Fight the Future (1998) ... when Darius Michaud Millennium (1996-1999) ... when Peter Watts Primal Fear (1996) ... when Bud Yancy Star Trek: The Next Generation-The Pegasus (1994) .... Admiral Erik Pressman Tombstone (1993) ... when City manager John Clum The Rocketeer (1991) ... when Howard Hughes Prisoners of the Sun (Australia: Blood Oath) (1990) ... when Maj. Beckett Stepfather II (1989) ... when Dr. Factor Clifford/The Stepfather Young Guns (1988) ... when Alex McSween The Stepfather (1987) ... when Jerry Blake SpaceCamp (1986) ... when Launch Director Places in the Heart (1984) ... when Chum Kelsey All the Right Moves (1983) ... when Freewoman Smith The Doctors (1981) ... when Dr. Jerry Dancy ''Heaven's Gate'' (1980) ... when Capt. Minardi