Shirley Ardell Mason, American psychiatric patient (died 1998)

Shirley Ardell Mason was an American art teacher who was reported to have dissociative identity disorder. Her life was purportedly described, with adaptations to protect her anonymity, in 1973 in the book Sybil, subtitled The True Story of a Woman Possessed by 16 Separate Personalities. Two films of the same name were made, one released in 1976 and the other in 2007. Both the book and the films used the name Sybil Isabel Dorsett to protect Mason's identity, though the 2007 remake stated Mason's name at its conclusion.

Psychiatry is the medical specialty devoted to the diagnosis, treatment, and prevention of deleterious mental conditions. These include matters related to cognition, perceptions, mood, emotion, and behavior.