John George Agar, Jr. (January 31, 1921 – April 7, 2002) was an American actor. He is best known for starring alongside John Wayne in the films Sands of Iwo Jima, Fort Apache, and She Wore a Yellow Ribbon. In his later career he was the star of B movies, such as Tarantula, The Mole People, The Brain from Planet Arous, Revenge of the Creature, Flesh and the Spur, and Hand of Death. He was the first husband of Shirley Temple.

Agar's career suffered in the wake of his divorce, but he developed a niche playing leading men in low-budget science fiction, Western, and horror movies in the 1950s and 1960s. John Wayne gave him several supporting roles in the late 1960s and early 1970s. In later years he worked extensively in television.