A former stage actor, Donald Castle was groomed for stardom by MGM in the late 1930s. Castle played Marian Hardy's (Cecilia Parker) beau Dennis Hunt in three of MGM's Andy Hardy features, but apparently he didn't catch on with audiences, in spite of his close resemblance to Clark Gable. He moved into character parts, playing both lawmen and disreputables in crime flicks and westerns. A close friend of actress Bonita Granville and her entrepreneur-husband Jack Wrather, Castle was part owner of a commercial 16-millimeter film production company run by Wrather, and in the 1950s and early 1960s served as associate producer for Wrather's TV series Lassie. Following a traffic accident in 1966, 49-year-old Don Castle died of a medication overdose.