Richard Hugh Lynch was born on February 12, 1940 (sometimes incorrectly cited as 1936) in Brooklyn, New York to Roman Catholic parents of Irish descent. His younger brother is actor Barry Lynch. Lynch served in the United States Marine Corps for four years.

Lynch's distinct scarred appearance made him a popular nemesis, and he can be seen in more than 100 film and television performances. The scars came from a 1967 incident in New York's Central Park in which, under the influence of drugs, he set himself on fire, burning more than 70% of his body. He spent a year in recovery, quit drugs and ultimately began training at The Actors Studio and at the HB Studio. In 1970, he co-starred with Robert DeNiro, Sally Kirkland and Diane Ladd in the short-lived off-Broadway play One Night Stands of a Noisy Passenger, written by Shelley Winters. He often played a villain in features, including Scarecrow, which marked his film debut, The Seven-Ups, Bad Dreams, The Sword and the Sorcerer, and Little Nikita.

His film credits included The Sword and the Sorcerer, Invasion USA, The Seven-Ups, Scarecrow, Little Nikita, Bad Dreams, God Told Me To, and Halloween. He appeared in science fiction productions, including Battlestar Galactica (as Wolfe) and its sequel series Galactica 1980 (as Commander Xaviar). He also appeared in such shows as Starsky and Hutch, Baretta, T. J. Hooker, Blue Thunder, Airwolf, The A-Team, Charmed and Star Trek: The Next Generation.

In 1982, Lynch won a Saturn Award for Best Supporting Actor for his performance as the evil King Cromwell in The Sword and the Sorcerer. Although Richard Lynch is best known for playing villains, he was cast as the President of the United States in the 2007 film Mil Mascaras vs. the Aztec Mummy. Lynch starred alongside Judson Scott in the 1982 short-lived science fiction TV series The Phoenix.

Through the years, Lynch worked with friend and colleague Don Calfa in the films Necronomicon (1993), Toughguy (1995), Corpses Are Forever (2003), and Lewisburg (2009).

In addition to acting, Lynch was a musician, and he played the saxophone, guitar, piano, and flute. He held Irish citizenship through his Irish-born parents and was a frequent visitor to Ireland. He starred together with brother Barry in the films Nightforce and Total Force. Lynch's wife Lily starred with him in the film Breaking the Silence (1998) and son Christopher Lynch starred with him in the science fiction film Trancers II. In 1977, Richard Lynch shared the stage with actor Al Pacino, a close friend, in the Broadway play The Basic Training of Pavlo Hummel. Lynch's portrayal of the wheelchair-bound Vietnam Vet garnered him a Tony nomination in 1977.

Lynch's body was found in his home in Yucca Valley, California on June 19, 2012. It is not known if Lynch died on June 18 or June 19. After not having heard from Lynch for several days, friend and Actress Carol Vogel went to his home to find the door open and his body in his kitchen. He was survived by his brother Barry and two sisters, Carole Taylor and Cathy Jones. News reports following his death incorrectly identified his birth year as 1936, but the obituary in the Los Angeles Times published by his family correctly listed the year as 1940.

Patrick Loubatière. Richard Lynch Forever (2013).

Lynch married twice — once to Béatrix Lynch (their son Christopher died in 2005 from pneumonia), and later to Lily Lynch.