1. Books about Dissociative Identity Disorder (DID), previously known as Multiple Personality Disorder:
* "The Haunted Self" by Colin A. Ross: A comprehensive and informative book on DID by a leading expert in the field.
* "I'm Not Crazy, I'm Just Not Me" by Kathy Steele: A personal account of one woman's experience with DID.
* "Sybil" by Flora Rheta Schreiber: A famous case study of a woman with DID, though the book has been criticized for its accuracy.
* "The Three Faces of Eve" by Corbett Thigpen and Hervey Cleckley: Another famous case study, detailing the lives of a woman with DID.
2. Books about characters with multiple personalities:
* "The Strange Case of Dr. Jekyll and Mr. Hyde" by Robert Louis Stevenson: A classic story about a man who transforms into a monstrous alter ego.
* "Fight Club" by Chuck Palahniuk: A novel exploring the concept of multiple identities and societal pressures.
* "The Girl on the Train" by Paula Hawkins: A psychological thriller featuring a character with unreliable narration and fragmented memories.
Please clarify your question by providing more context. For example, what genre are you interested in? Are you looking for a fictional story or a non-fiction book about DID?