He attended Central Michigan University in Mount Pleasant, Michigan, and the University of Iowa in Iowa City, Iowa.
Terry O'Quinn began acting in the 1970s. He has appeared in such films as Tombstone and Heaven's Gate.
After a 2002 appearance on Alias, he became a favorite of yet another TV producer, this time J.J. Abrams. Following a seven-episode guest run on The West Wing in 2003 and 2004, Terry got a call from Abrams indicating that the producer wanted to cast him (without any audition needed) in his new television drama Lost, about a group of people stranded on a mysterious island after a plane crash.
Terry later admitted on the TV Guide Channel that he didn't have much faith in the series at first, calling it "The Mysterious Gilligan's Island of Dr. Moreau."
In July 2005, he received an Emmy nomination for best supporting actor in a drama for his work as John Locke on Lost.
He has been married to his wife, Lori, for 25 years. He has 2 sons - Jack Conway and Rob Wiper who live on the West Coast of the United States.