The fresh-faced appeal and promising talent of darkly handsome "B" actor Don Castle was evident from the late 30s into the 40s, but it wasn't enough for him to reach topgrade stardom. Born Marion Goodman, Jr. in Beaumont Texas in 1918 and raised in Houston, Don enrolled at the University of Texas before heading West to California to try his luck in acting.

An agent was struck by his resemblance to a young Clark Gable and took him to MGM, who went on to sign the 20-year-old actor wannabe (young Marion had already changed his name to Don Castle). The nascent actor was groomed very slowly and started at the bottom step of the billing ladder with numerous small, often uncredited roles in such films as Young Dr. Kildare (1938), Nick Carter, Master Detective (1939), La Konga (1940), The Ghost Comes Home (1940) and Bu Kadın Benimdir (1940). On a very rare occasion MGM would better feature their client in support as in the comedy Rich Man, Poor Girl (1938) which starred Robert Young and Ruth Hussey in the title roles with Don as part of Hussey's zany family, and also as Dennis Hunt in Love Finds Andy Hardy (1938), a role he played again in Out West with the Hardys (1938). Appearing in several MGM shorts but, for the most part, interest in their client quickly waned.

Paramount picked the young actor up and cast him in a smallish role in You're the One (1941), a vehicle for the then-popular jazz and popular standards singer (Wee) Bonnie Baker. His second film, the war-era drama Power Dive (1941), a loanout, finally gave Don a chance to show his potential in a second lead role as test pilot Richard Arlen's brother and rival for Jean Parker. Don also showed strong ability in Tombstone: The Town Too Tough to Die (1942) with Richard Dix playing Wyatt Earp and Don fourth billed as Johnny Duanne.

WWII interrupted his career when he was drafted into the Army Air Force. During that time he made training films for the First Motion Picture Unit. Don returned to Paramount following his 1946 discharge but little interest was shown. A small role in The Searching Wind (1946), a war drama, was all he could muster. On his own, Don finally received top billing in the "Poverty Row" programmer Lighthouse (1947) in which he and fellow lighthouse keeper (played by John Litel) vie for the affections of pretty June Lang. He then went and co-starred with Johnny Sands and Vivian Austin in the cheapjack racing yarn Born to Speed (1947).

Don forged a strong friendship with former child actress Bonita Granville after co-starring with her in the Monogram film noir The Guilty (1947), The friendship proved quite fruitful. He was then cast in the Wrather Production Company's drama High Tide (1947) with Lee Tracy and Julie Bishop and again appeared opposite Bonita in Strike It Rich (1948). Don went on to serve as "best man" when Bonita married studio head Jack Wrather in 1947.

Most of Don's lead/support parts in subsequent bargain-basement independents were equally unrewarding -- The Invisible Wall (1947), Roses Are Red (1947), Perilous Waters (1948), Madonna of the Desert (1948), Who Killed 'Doc' Robbin? (1948), I Wouldn't Be in Your Shoes (1948) and Stampede (1949). He subsequently signed a three-picture contract with Lippert Productions but only one, Motor Patrol (1950), was ever filmed. When movie offers completely dried up in 1950, Don found some brief work as a guest on TV anthology programs.

During the lean years in the early 1950s, Don and his second wife, Zetta, opened Castle's Red Barn (1959) in Palm Springs which became a popular place to stay. They ran it for seven years. In 1957, he was given minor roles in the films Canavarlar yatağı (1957) and Vahşi mücadele (1957). Jack and Bonita Wrather came to Don's rescue once again when Jack made Don president of International Television Corporation. He also served as an associate producer of Wrather's classic series Lassie (1954) from 1960-1962.

Don's later years were marred by depression. Divorced from his second wife in 1962, he died from a drug overdose at the age of 47.