Treehouse of Horror is an annual series of special Halloween-themed episodes of the animated sitcom The Simpsons, with 33 anthology episodes between 1990 and 2022. 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. The eponymous first installment "Treehouse of Horror" aired October 25, 1990, during the second season, broadly inspired by EC Comics horror tales. In addition to parodies of horror, science fiction, and fantasy films, episodes include the recurring alien characters Kang and Kodos, unique opening sequences, and "scary" pseudonyms in the credits. Treehouse of Horror episodes have earned high ratings and broad popularity, spawning a steady stream of merchandise. Segments Treehouse of Horror episodes typically consist of four parts: an opening and Halloween-themed version of the credits, followed by three segments. These segments usually have a horror, science fiction or fantasy theme and quite often are parodies of films, novels, plays, television shows, Twilight Zone episodes, or old issues of EC Comics. Although they are sometimes connected by "wraparounds", the three segments rarely have any kind of continuing connection within the episode. Some have recurring elements, such as "Treehouse of Horror V", in which Groundskeeper Willie is killed by an axe in a similar fashion in all three segments. The episodes are considered to be non-canon, which means they always take place outside the normal continuity of the show, since each character appears to be fine afterwards. From "Treehouse of Horror" to "Treehouse of Horror XIII" and resuming with Treehouse of Horror XXXIII all three segments were written by different writers. In some cases there was a fourth writer who wrote the opening and wraparound segments. For the original "Treehouse of Horror", there were three different directors for the episode. Starting with season 15's "Treehouse of Horror XIV", however, only one writer has been credited with writing each Treehouse of Horror episode. On occasion, the episodes will be used to showcase special animation, such as the "Treehouse of Horror VI" segment "Homer3", in which a computer-animated Homer is shown in a non-animated setting. At the time (1995), it was groundbreaking, as it was unusual for a television show to use such animation. The segment was