Ann Rae Rule (née Stackhouse) was an American author of true crime books and articles, famous for her vivid and insightful portrayal of criminal cases.

She was born on October 22, 1931, in Lowell, Michigan, U.S. Raised in a law enforcement and criminal justice system environment, Rule grew up aspiring to work in law enforcement herself. She was a former Seattle Policewoman and was well-educated in psychology and criminology.

Ann Rule gained prominence with her first book, The Stranger Beside Me (1980), which detailed her experiences with the infamous serial killer Ted Bundy. At the time she started researching the book, the murders were still unsolved, and the identity of the killer, who turned out to be Bundy, was a shocking revelation as Bundy was her friend and colleague at the Seattle, Washington Crisis Clinic. This unique perspective set her apart in the true crime literary world.

Rule authored over 30 true crime books, including notable works such as Small Sacrifices, about Oregon child murderer Diane Downs. Many of her books focused on murder cases that occurred in the Pacific Northwest and particularly in her adopted home state of Washington.

Throughout her career, Rule was recognized for her contributions to the genre, winning two Anthony Awards from Bouchercon, the mystery fans' organization.

She passed away on July 26, 2015.