Treehouse of Horror is a series of annual Halloween-themed anthology episodes of the American animated sitcom The Simpsons. Also known as The Simpsons Halloween Specials, each episode typically consists of three separate, self-contained segments. Each segment involves the Simpson family in some comical horror, science fiction, or supernatural setting; plot elements operate beyond the show's normal continuity, with segments exaggeratedly more morbid and violent than a typical Simpsons episode. With 36 episodes as of 2025, each Treehouse of Horror episode is numbered in Roman numerals, one less than the respective season it is in; the tradition began with the second season.