Born in Cheyenne, Wyoming, Mildred Harris made her first screen appearances at the age of eleven in the Francis Ford and Thomas H. Ince directed 1912 Western film short The Post Telegrapher then went on to play a variety of juvenile roles, including turns in the Oz film series produced by The Wonderful Wizard of Oz author L. Frank Baum. She was a prominent child actor throughout the 1910s. She eventually graduated to leading lady assignments, working under the direction of such prominent filmmakers as Cecil B. DeMille and D.W. Griffith throughout the 1910s. In 1914, she was hired by The Oz Film Manufacturing Company to portray Fluff in The Magic Cloak of Oz and Button-
She appeared in 132 films in her career from 1912 to 1944.