Marion Eleanor Zimmer Bradley was an American author of fantasy, historical fantasy, science fiction, and science fantasy novels. She is best known for the Arthurian fiction novel The Mists of Avalon and the Darkover series, noted for their feminist perspective.

Bradley began writing at the age of 17 and later graduated with a Bachelor of Arts degree from Hardin-Simmons University. She co-founded the Society for Creative Anachronism in 1966 and served as the editor of the long-running Sword and Sorceress anthology series.

Her first story was sold to Vortex in 1952. Early in her career, she used pseudonyms for stories outside the speculative fiction genre, including some gay and lesbian pulp fiction novels such as I Am a Lesbian (1962). In 2000, she was posthumously awarded the World Fantasy Award for lifetime achievement.

Bradley's reputation was marred posthumously when it was revealed that she was guilty of child sexual abuse, and for allegedly assisting her second husband, convicted child abuser Walter Breen, in sexually abusing multiple unrelated children. Many science fiction authors have since publicly condemned Bradley.