Gary Lockwood was born John Gary Yurosek in Van Nuys, California to John and Margaret Emma (Kiel) Yurosek . He attended UCLA on a football scholarship.
He began his career as a movie stuntman, and a stand-in for Anthony Perkins, prior to his acting debut in 1959 in an uncredited bit role in Warlock (1959). He also appeared as a police officer in The Case of the Romantic Rogue (1959). Two series came early in his career, ABC's Hawaii-set Follow the Sun (1961) (1961-62) as an adventurous magazine writer in Honolulu. In 1961, he appeared as a rodeo cowboy in love with an 18-year-old singer (played by Tuesday Weld) in ABC's Cherie (1961). He then starred with Jeff Bridges in My Daddy Can Lick Your Daddy (1963). In 1964, he starred as a young U.S. Marine lieutenant in the NBC series, The Lieutenant (1963). He then starred in another NBC television series, Kraft Mystery Theater (1961), opposite Sally Kellerman (with whom he would later appear in the second Star Trek (1966) pilot, Where No M