[2] On Broadway, as Ian Keith, he performed in The Andersonville Trial (1959), Edwin Booth (1958), Saint Joan (1956), Touchstone (1953), The Leading Lady (1948), A Woman's a Fool - to Be Clever (1938), Robin Landing (1937), King Richard II (1937), Best Sellers (1933), Hangman's Whip (1933), Firebird (1932), Queen Bee (1929), The Command Performance (1928), The Master of the Inn (1925), Laugh, Clown, Laugh!

Keith had a major role as a gambler in director Raoul Walsh's 1930 widescreen western The Big Trail starring John Wayne.

This established him as a dependable supporting player, and he went on to play dozens of roles—including Octavian (Augustus) in Cleopatra—in major and minor screen fare for the next three decades.

He also had a definite flair for comedy, and his florid portrayal of the comic-strip ham actor "Vitamin Flintheart" in Dick Tracy vs. Cueball was so amusing that he repeated the role in two more films.

[4] In 1955, he was seen on screen in his only Shakespeare role, when he made a cameo appearance as the Ghost opposite Richard Burton's Hamlet in a sequence from the Edwin Booth biopic Prince of Players.