The Crypt Keeper in Gerald's Game — AKA the "Moonlight Man" — is based on a notorious real-life killer. From the moment that Stephen King broke through with his first published novel Carrie, production companies have rushed to adapt his books for movies and TV. This naturally began with Brian DePalma's haunting version of Carrie. However, in 2017, a young director named Mike Flanagan took on his first Stephen King adaptation with a movie that some called unfilmable. This was Gerald's Game, and it remains a haunting horror movie.
https://screenrant.com/geralds-game-movie-crypt-creeper-real-life-ed-gein/