A native of Los Angeles County, Marshall was just past his fifth birthday when the first film in which he appeared, Roughly Speaking, a comedy-drama starring Rosalind Russell and Jack Carson, started production in April 1944, finishing in mid-July.
Also in 1951, his television debut, at the age of 12, in an episode of The Adventures of Wild Bill Hickok, a western series aimed at pre-teens and young adolescents, was broadcast on December 30.
Upon becoming a teenager, he found roles becoming scarce, with his only work in 1953 consisting of an episode of the popular William Bendix sitcom, The Life of Riley, playing Egbert Gillis, the son of Riley's best friend, Jim Gillis and, in 1954, there was one film, Tanganyika, along with a David Niven episode of CBS' Four Star Playhouse, airing on February 18.
Although he was one of three teenage actors, along with Richard Beymer and ultimate choice Sal Mineo, tested by director Nicholas Ray for the key supporting role of the protagonist's sensitive friend Plato in 1955's Rebel Without a Cause,[1] there was no work for him that year and the sole acting assignment in 1956 was another appearance as Egbert on The Life of Riley.
[2] His final three screen acting roles came the following year, with another turn as Egbert on The Life of Riley, an episode of the syndicated series The Silent Service and an unbilled bit in the attempted revival of the Andy Hardy film series, Andy Hardy Comes Home.