Annabelle is an allegedly-haunted Raggedy Ann doll, housed in the now closed occult museum of the paranormal investigators Ed and Lorraine Warren. Annabelle was moved there after supposed hauntings in 1970. A character based on the doll is one of the antagonists that appear in The Conjuring Universe.
Annabelle is the orchestrator of the madness. While the film's plot is fictional, Judy Warren now Judy Spera is an actual person, whom Dauberman consulted with while writing the movie. Judy and Tony Spera (her husband) have been very helpful since the early days [of the Conjuring franchise], says Dauberman.