Film

Morgan debuted in film The Suspect in 1916 and the following year he starred with John Barrymore in Raffles, the Amateur Cracksman (1917), an independent film produced in and about New York City. His career expanded when talkies began. Although the befuddled but good-hearted middle-aged man became his stereotypical role, he played romantic leads in such films as When Ladies Meet (1933) and Enchanted April (1935). By the mid-1930s, Metro-Goldwyn-Mayer was so impressed by Morgan that they signed him to a lifetime contract.^{[citation needed]} In 1936 Morgan played alongside Shirley Temple as Professor Appleby in Dimples.

Morgan is best remembered for his performance in The Wizard of Oz (1939), in which picture he played a total of six roles, most notably the Wizard, which included the carnival huckster "Professor Marvel", the gatekeeper at the Emerald City, the coachman of the carriage drawn by "The Horse of a Different Color", the Emerald City guard (who initially refuses to let Dorothy and her friends in to see the Wizard), and the Wizard's scary face projection. Morgan was cast in the role on September 22, 1938. W. C. Fields was originally chosen for the part of the Wizard, but the studio ran out of patience after protracted haggling over his fee.

An actor with a wide range, Morgan was equally effective playing comical, befuddled men such as Jesse Kiffmeyer in Saratoga (1937) and Mr. Ferris in Casanova Brown (1944), as he was with more serious, troubled characters like Hugo Matuschek in The Shop Around the Corner (1940), Professor Roth in The Mortal Storm (1940) and Willie Grogan in The Human Comedy (1943). MGM's musical comedy film The Great Morgan (1946), is a compilation film featuring Frank Morgan supposedly as himself but playing the familiar bumbler. Occasionally a co-star (as in The Human Comedy, and, once established, invariably a featured player), he also saw the occasional lead deep in his Hollywood career, as the philanthropic tycoon falsely accused of murder in 1941's Washington Melodrama and The Great Morgan (in which he is the Morgan of the title, the picture's central player).

During the 1940s Morgan appeared in such diverse genres and roles as an oil wildcatter in Boom Town (supporting Clark Gable, Spencer Tracy, and Claudette Colbert); Tortilla Flat in 1942 (based on the John Steinbeck book, again supporting Tracy); a jungle doctor in White Cargo (supporting Walter Pidgeon and Hedy Lamarr); a shepherd in the Courage of Lassie in 1946; a doctor again in Green Dolphin Street in 1948 in support of Lana Turner, Van Heflin, and Donna Reed; King Louis XIII in The Three Musketeers in 1948, supporting Gene Kelly and Turner again; and as Jimmy Stewart’s boss in The Stratton Story in 1949. He played a fire chief in his final picture, Key to the City, filmed in 1949 but released posthumously in 1950.

Radio

Morgan also had a career in radio. In the 1940s, Morgan co-starred with Fanny Brice in one version (of several different series) of the radio program Maxwell House Coffee Time, aka The Frank Morgan-Fanny Brice Show. During the first half of the show Morgan would tell increasingly outlandish tall tales about his life adventures, much to the dismay of his fellow cast members. After the Morgan segment there was a song, followed by Brice as 'Baby Snooks' for the last half of the show. When Brice left to star in her own program in 1944, Morgan continued solo for a year with The Frank Morgan Show.^[7] In 1947, Morgan starred as the title character in the radio series The Fabulous Dr. Tweedy. He also recorded a number of children's records, including the popular Gossamer Wump, released in 1949 by Capitol Records.