Marion Eleanor Zimmer Bradley (June 3, 1930 September 25, 1999) was an American author of fantasy, historical fantasy, science fiction, and science fantasy novels. She is best known for her Arthurian fiction novel The Mists of Avalon and the Darkover series. Renowned for the feminist perspective in her writing, Bradley's legacy is complex due to posthumous allegations by her daughter Moira Greyland of child sexual abuse, and accusations that she enabled her second husband, convicted child abuser Walter Breen, in his criminal activities.

Bradley began writing at the age of 17 and achieved her first literary sale in 1952. She graduated with a Bachelor of Arts degree from Hardin-Simmons University and moved to Berkeley, California, for graduate studies at the University of California, Berkeley. In 1966, she co-founded the Society for Creative Anachronism. Bradley also served as the editor of the long-running Sword and Sorceress anthology series. Unfortunately, her reputation has been overshadowed by the serious allegations made by her children.

In response to the revelations about Bradley's personal life, the publisher of her digital backlist decided to donate all income from her e-books to the charity Save the Children. As a result of the allegations, several science fiction authors have publicly condemned Bradley.

Despite the controversy, Bradley's influence on the genres of science fiction and fantasy remains significant, with her works continuing to be read and discussed within the literary community. She was posthumously awarded the World Fantasy Award for lifetime achievement in 2000.