Marilyn Adele Dunlap was born on March 5, 1924 (for her stage name she took her nickname, Myrna, and shortened her middle name, Adele, to "Dell", which she used as her last name). She started her career as a showgirl in the famous Earl Carroll Revue in New York, and made her film debut in A Night at Earl Carroll's (1940). Signed by MGM, she appeared in Ziegfeld Yıldızları (1941), but MGM didn't pick up her option and she returned to Earl Carroll's. She soon was appearing at the Billy Rose Nightclub, then spent a season in the "George White's Scandals" revue. However, the taste of Hollywood never left her, and she went back in 1943 and appeared in a string of westerns with such cowboy icons as Bob Steele and Hoot Gibson. She had a small part in the classic Thirty Seconds Over Tokyo (1944), and shortly afterwards signed a contract with RKO Pictures. RKO kept her busy, putting her in more than 20 films over the next few years, even appearing with future US President Ronald Reagan in the 1949 comedy The Girl from Jones Beach (1949). She gave a good performance in an atypical role as the ambitious, murderous daughter of a powerful rancher in the offbeat western İblisin Kızı (1951). She worked steadily over the years, not only in films but on TV as well, and had a recurring role in the Dan Duryea adventure series China Smith (1952). At one point she wrote a gossip column, "Hollywood: Then and Now".