Violet Mary Firth Evans (better known as Dion Fortune), was a British occultist and author. Her pseudonym was inspired by her family motto "Deo, non fortuna" (Latin for "by God, not fate").

From 1919 she began writing a number of novels and short stories that explored various aspects of magic and mysticism, including The Demon Lover, The Winged Bull, The Goat-Foot God, and The Secrets of Dr. Taverner. This latter is a collection of short stories based on her experiences with Theodore Moriarty. Two of her novels, The Sea Priestess and Moon Magic, became influential within the religion of Wicca, especially upon Doreen Valiente.

Of her non-fiction works on magical subjects, the best remembered of her books are; The Cosmic Doctrine, meant to be a summation of her basic teachings on mysticism; The Mystical Qabalah, an introduction to Hermetic Qabalah; and Psychic Self Defence, a manual on how to protect oneself from psychic attacks. Though some of her writings may seem dated to contemporary readers, they have the virtue of lucidity and avoid the deliberate obscurity that characterised many of her forerunners and contemporaries.