American writer, known especially for her Darkover series of science fiction novels and for her reimaginings of Classical myths and legends from women characters' perspectives.

Marion Zimmer studied at the New York State College for Teachers from 1946 to 1948 and, after her career was established, graduated from Hardin-Simmons College in 1964. In 1949 she married Robert A. Bradley, from whom she later was divorced. She retained his name professionally.

Bradley was a prolific writer, producing numerous historical, fantasy, and gothic novels and short stories under her own name and several pseudonyms. She is, however, best known for her many science fiction novels and stories. She published her first important work, the story "Centaurus Changeling," in 1954. Her first novel, The Door Through Space, appeared in 1961. Two more novels, The Sword of Aldones and The Planet Savers, were published in 1962. Both take place on Darkover, a planet that is home to a lost Terran (Earth) colony. It became the setting for a series of more than 20 science fiction novels by Bradley; other writers also set their own work on Darkover.

Bradley achieved best-seller status with The Mists of Avalon (1982), a retelling of the Arthurian legend with an emphasis on the female characters. Similarly, The Firebrand (1987) reworked the Iliad from the perspective of the female characters. Bradley subsequently wrote several prequels to The Mists of Avalon, including The Forest House (1994) and Lady of Avalon (1997), and in 1995 she introduced the Light series. Many of her later novels were written in collaboration with other authors, notably Diana L. Paxson. Bradley also edited Marion Zimmer Bradley's Fantasy Magazine, which she started in 1988.