Mark Harmon (born September 2, 1951) is an American actor who has been starring in U.S. television programs and films since the mid-1970s, after a career as a collegiate football player with the UCLA Bruins. Since 2003, Harmon has starred as Leroy Jethro Gibbs in the CBS series NCIS.
Harmon was born Thomas Mark Harmon in Burbank, California. His father was University of Michigan football All-American and Heisman Trophy winner Tom Harmon. His mother is actress and artist Elyse Knox (née Elsie Lillian Kornbrath). Harmon has two older sisters, actress and painter Kristin Nelson, the former wife of singer Ricky Nelson, and actress Kelly Harmon, who was once married to car magnate John DeLorean.
After attending Los Angeles Pierce College as a student and quarterback, Harmon transferred to the University of California, Los Angeles and, following in his father's athletic footsteps, was the starting quarterback for the UCLA Bruins football team in 1972 and 1973, engineering a stunning upset of the two-time defending national champion Nebraska Cornhuskers in 1972. He received the National Football Foundation Award for All-Round Excellence in 1973. In his two years as quarterback in coach Pepper Rodgers' wishbone offense, UCLA won 17 games and lost only 5. He graduated from UCLA with a B.A. in Communication cum laude in 1974.