(written from a Production point of view)
Born in Lynn, Massachusetts, he appeared in several films starring Marlon Brando, beginning with an uncredited role in the 1950 film The Men, which was his acting debut. TOS star DeForest Kelley also made an uncredited appearance in this film. Gilman followed this with an appearance in Brando's The Wild One in 1953. That same year, he appeared in the biblical epic The Robe, starring Jean Simmons, who would co-star with Marlon Brando the following year in Desirée, in which Gilman also appeared. Jay Robinson and Michael Ansara also starred in The Robe, while John Hoyt co-starred in Desirée.
His other film credits include Away All Boats (1956, with Keith Andes, Don Keefer, Parley Baer, Hal Baylor, and Chuck Courtney), PT 109 (1963, with James Gregory, Biff Elliot, and George Takei), Every Which Way But Loose (1978, with Roy Jenson and William O'Connell), and the Marlon Brando films The Young Lions (1958, also with Baer and Baylor, as well as Paul Comi, Robert Ellenstein, and Michael Pataki), One-Eyed Jacks (1961, with Elisha Cook, Jr.), and The Missuori Breaks (1976, with John McLiam).
Gilman also made guest appearances on such television series as The Untouchables, Gunsmoke, and The Life and Times of Wyatt Earp.
Both he and Ron Soble remained very good friends until his death.
He died in North Hollywood, California in 1985.