Marion Davies (born Marion Cecilia Douras; January 3, 1897 – September 22, 1961) was an American actress, producer, screenwriter, and philanthropist. Educated in a religious convent, Davies left the school to pursue a career as a chorus girl. As a teenager, she appeared in several Broadway musicals and one film, Runaway Romany (1917). She soon became a featured performer in the Ziegfeld Follies. While performing in the 1916 Follies, the nineteen-year-old Marion met the fifty-three-year-old newspaper tycoon, William Randolph Hearst, and became his mistress. Hearst took over management of Davies' career and promoted her as a film actress.

Hearst financed Davies’ pictures and promoted her career extensively in his newspapers and Hearst newsreels. He founded Cosmopolitan Pictures to produce her films. By 1924, Davies was the number one female box office star in Hollywood because of the popularity of When Knighthood Was in Flower and Little Old New York, which were among the biggest box-office hits of their respective years. During the zenith of the Jazz Age, Davies became renowned as the hostess of lavish soirees for Hollywood actors and political elites. However, in 1924, her name became linked with scandal when film producer Thomas Ince died at a party aboard Hearst's yacht.

Following the decline of her film career during the Great Depression, Davies struggled with alcoholism. She retired from the screen in 1937 to devote herself to an ailing Hearst and charitable work. In Hearst's declining years, Davies remained his steadfast companion until his death in 1951. Eleven weeks after Hearst's death, she married sea captain Horace Brown. Their marriage lasted until Davies' death at 64 from malignant osteomyelitis (bone cancer) of the jaw in 1961.

By the time of her death, her popular association with the character of Susan Alexander Kane in the film Citizen Kane (1941) already overshadowed Davies' legacy as a talented actress. The title character's second wife—an untalented singer whom he tries to promote—was widely assumed to be based upon Davies. However, many commentators, including writer-director Orson Welles, defended Davies' record as a gifted actress and comedienne to whom Hearst's patronage did more harm than good. In his final years, Welles attempted to correct the widespread misconceptions the film had created about Davies' popularity and talents as an actress.

Marion Cecilia Douras was born on January 3, 1897, in Brooklyn, the youngest of five children born to Bernard J. Douras, a lawyer and judge in New York City and Rose Reilly. Her father performed the civil marriage of socialite Gloria Gould Bishop. She had three older sisters, Ethel, Rose, and Reine. An older brother, Charles, drowned. His name was subsequently given to Davies' nephew, screenwriter Charles Lederer, the son of Davies' sister Reine Davies.

The Douras family lived near Prospect Park in Brooklyn. Educated in the Sacred Heart religious convent near the Hudson River and later a religious convent near Tours, France, Davies was uninterested in her academic studies and very unhappy as a child supervised by Catholic nuns. Her family was close friends with architect Stanford White, and Davies grew up learning about the Evelyn Nesbit sex scandal.

Davies struggled with her stutter as a child, and convinced her mother to let her leave school early due to the torment of her classmates and teachers. As a teenager, Marion left school to pursue a career as a showgirl. When her sister Reine adopted the stage name of Davies after seeing a real estate billboard advertisement, Marion followed suit.

Davies worked as a chorus line dancer starting with Chin-Chin, a 1914 musical starring David C. Montgomery and Fred Stone, at the old Forrest Theatre in Philadelphia. She made her Broadway debut starring in the show at the Globe Theatre on October 20. She also appeared in Nobody Home, Miss Information and Stop, Look and Listen. When not dancing, she modeled for illustrators Harrison Fisher and Howard Chandler Christy.