Marion was born in Albany, New York on the third of June in 1930. She was born to Leslie Raymond Zimmer, who worked as a carpenter, and Evelyn Conklin Zimmer, who was a historian. Marion was baptized at the age of seventeen, on July 5, 1947 at Christ Church Cathedral (Episcopal) in Hartford, Connecticut. In the 1980’s, Marion was a neopagan but by the 1990’s she had returned to the Episcopalian religion. Bradley told an interviewer: "I just go regularly to the Episcopalian church. . . . That pagan thing, I don't object to it, but I feel that I've gotten past it.” Marion married at an extremely young age to an older man from Texas named Robert Alden Bradley, and they stayed with each other from October 26, 1949 until their divorce on May 19, 1964. With Robert, Marion Bradley had a son named David Robert Bradley. Later on, Marion married a man by the name of Walter H. Breen on June 3, 1964. They had a daughter named Moira Greyland, who went on to become a professional harpist and singer, and a son, Patrick, later to be known as Mark. In 1965, Marion Zimmer graduated with a Bachelor of Arts degree from Hardin-Simmons University in Abilene, Texas. After graduation, Marion moved to California in order to pursue graduate studies, and in 1966, she ended up helping to found and name the Society for Creative Anachronism and was involved in developing several local groups of the same variant.
Bradley wrote many books, anthologies, and poems. It was more common for her to write full books, but she