John Hart, a tall and athletic individual with "movie star" good looks, began his acting career on the stage of the prestigious Pasadena Playhouse in his youth. He made his screen debut in a supporting role in director Cecil B. DeMille's big-budget film, The Buccaneer, released in 1938.
As a native Los Angeleno, Hart seemed destined for greater things, but his early momentum was slowed by military service. After World War II, he returned to Hollywood, only to find himself back at the starting line. Hart eventually fell into the low-budget Western and serial genre, but he made a notable impact in many youth-oriented productions.
One of his most notable roles was as the embodiment of radio-comic strip hero Jack Armstrong in a 1947 serial. He also rode the Western plains in 52 episodes of TV's The Lone Ranger, playing the Masked Man, and brought James Fenimore Cooper's courageous frontiersman Hawkeye to life in TV's Hawkeye and the Last of the Mohicans, released in 1957.
In recent years, Hart transitioned behind the camera, working as a cameraman, post-production supervisor, dubbing supervisor, and more.