Ann Rae Rule (née Stackhouse; October 22, 1931 – July 26, 2015) was an American author best known for her true crime books and articles. Her most famous work, The Stranger Beside Me (1980), details the life of notorious serial killer Ted Bundy, who was her co-worker and friend before his crimes were revealed. Rule authored over 30 true crime books, including Small Sacrifices, about Oregon child murderer Diane Downs. Many of her books focus on murder cases from the Pacific Northwest and her home state of Washington.

Raised in a law enforcement environment, Rule initially aspired to work in law enforcement, having been a former Seattle Policewoman and being well-versed in psychology and criminology. Her unique perspective, particularly due to her personal connection with Bundy, distinguished her in the true crime genre. Rule was also recognized with two Anthony Awards from Bouchercon, the mystery fans' organization.