Peggy O'Neill was born Barbara Jeanne O'Neill on April 8, 1924 in San Francisco, California. When she was eighteen she won a beauty contest and moved to Hollywood. She met producer Charles Rogers who helped her get a screen test. Peggy was given a starring role in the 1944 comedy Song Of The Open Road. Columnist Louella Parsons called her "Hollywood's newest Cinderella". During the Summer of 1944 Peggy went in a bond selling tour of Texas with Adele Mera and Gale Storm. She had small parts in the movies It's A Pleasure and The Hoodlum Saint.
Peggy impulsively married Lloyd Miner, an Army officer, on January 16 1945. They separated shortly after the wedding and Peggy moved in with her mother. In the Spring of 1945 Peggy was offered a long term contract with Paramount. She started a serious romance with screenwriter Albert Mannheimer. On April 12, 1945 Peggy had an argument with Albert. That evening she committed suicide by taking an overdose of sleeping pills. She was only twenty-one years old. Peggy was buried at Calvary Cemetery in Los Angeles.