Her father was Irish Philadelphian newspaperman, Benny McNulty. He was related to Jim Farley Roosevelts campaign managers and later Postmaster General. As a child, she sang songs at a silent movie theater. After the sixth grade she joined a touring vaudeville act called The Kiddie Kabaret. Billed as Penny McNulty, she sang and danced with Milton Berle and Gene Raymond. Her first speaking part was in a Jack Benny Broadway show Great Temptations. Moving to Hollywood, she took a new name after marrying dentist Lawrence Singleton. Her first name derived from having saved large amounts of penny coins. She played a tough nightclub dancer in After the Thin Man (1936) and acted/sang/danced in Swing Your Lady (1938), one of the movies Humphrey Bogart regarded as his worst. Though naturally a brunette, she bleached her hair blonde ever since she got the role of Blondie in that long-lived series.