Of Greek and Irish heritage, she was born Marion Douras in Brooklyn, New York. Her parents were Herbert Douras, a lawyer who moved in New York City political circles and Rose Reilly, formerly of Jersey City, New Jersey.
Marion was the youngest of five children. Her elder siblings included Rose, Reine, and Ethel. A brother, Charles, died at the age of 15 from drowning in 1906.
The Douras brood lived near Prospect Park in Brooklyn, but already the bright lights of Manhattan beckoned to the sisters. They all became showgirls on the Great White Way, where Florenz Ziegfeld was beginning his spectacular annual "Ziegfeld Follies" shows. These shows were considered the high end of vaudeville.
The girls changed their surname to Davies, which one of them spotted from a realtor's sign in the neighborhood. Even as New York was the melting pot for new immigrants, having a WASP surname greatly helped one's prospects.
Marion outshone her siblings with a 20-year movie career, playing light comedic roles well into the 1930s and giving generous financial assistance to her family and friends. These facts are still overshadowed by her relationship with William Randolph Hearst, who was married to former showgirl turned society grande dame Millicent Veronica Willson, and her fabulous life as hostess at San Simeon and Ocean House in Santa Monica. Her career, however, was hampered by Hearst's insistence that she play distinguished, dramatic parts, as opposed to the comic roles that were her forte, as well as her increasing dependence on alcohol (she used to hide bottles of liquor in San Simeon's toilet tanks).
Ten weeks after the death of William Randolph Hearst, Marion Davies married for the first time, at the age of 54, on October 31, 1951. Her husband was a former sea captain and policeman and sometime actor, Horace G. Brown. It was not a happy marriage: Marion filed divorce papers twice but no divorce was ever finalized.
During the lifetime of Davies' niece Patricia Lake (née Van Cleeve), the latter was said to be the daughter of Marion Davies's sister Rose Davies and her first husband, George Van Cleeve. (Patricia married Arthur Lake, who played Dagwood in numerous films.) After Patricia's death, her family announced that she was in fact the daughter of Marion Davies and William Randolph Hearst, though this claim does not appear to have been verified independently.