Dennis Morgan had worked on the stage and in radio as an actor and singer before he moved to Hollywood in the mid-'30s. First as Stanley Morner then Richard Stanley, he made several films, singing in Suzy, a starring vehicle for Jean Harlow and Cary Grant, and The Great Ziegfeld (both 1936), although dubbed in the latter by Allan Jones. Other 30s films include Men with Wings (1938) and Waterfront (1939). Signed by Warner Bros., he became Dennis Morgan and made an impact in Kitty Foyle: The Natural History of a Woman (1940), with Ginger Rogers. This led to leading roles in action films and light comedies.
He appeared in Affectionately Yours (1941), with Merle Oberon and Rita Hayworth, In This Our Life (1942) and Thank Your Lucky Stars (1943), the latter starring Eddie Cantor and featuring hordes of Warner contract players doing their bit for the war effort, including Bette Davis singing "They're Either Too Young or Too Old." That same year Morgan had his biggest role to date, starring as the Red Shadow in the Sigmund Romberg/Oscar Hammerstein II musical The Desert Song (1943).
In 1944, he made The Very Thought of You and Shine on Harvest Moon, a biopic starring Ann Sheridan as vaudeville star Nora Bayes. Another biopic, in which Morgan played singer Chauncey Olcott with Arlene Dahl as Lillian Russell, was My Wild Irish Rose (1947). Teamed with Jack Carson, Morgan made a series of comedies with music: Two Guys from Milwaukee and The Time, The Place and the Girl (both 1946), Two Guys from Texas (1948) and It's a Great Feeling (1949), the latter featuring guests spots from Doris Day, Danny Kaye and others. Morgan appeared in One Sunday Afternoon (1948), a musical remake of the 1933 film.
In the '50s, he made Perfect Strangers (with Rogers) and Pretty Baby (both 1950), Painting the Clouds with Sunshine (1951, which was one of several screen versions of Avery Hopwood’s play, The Gold Diggers), Pearl of the South Pacific (1955), and Uranium Boom (1956). Also, he was on television in series such as 21 Beacon Street (1959), Petticoat Junction (1968), and The Love Boat (1980). Morgan virtually retired from film in the late '50s, but returned to play a cameo role in Won Ton Ton, The Dog Who Saved Hollywood (1976).