This is a list of Treehouse of Horror episodes from the animated television series The Simpsons. Treehouse of Horror episodes have aired every year since the second season (1990). Each episode has three separate segments. These segments usually involve the family in some horror, science fiction, or supernatural setting. They always take place outside the normal continuity of the show and are therefore considered to be non-canon.

The first "Treehouse of Horror" episode aired on October 25, 1990 and was inspired by EC Comics Horror tales. Before "Treehouse of Horror XI", which aired in 2000, every episode was aired in the week preceding or on October 31; "Treehouse of Horror II" and "Treehouse of Horror X" are the only episodes to air on Halloween. However, due to Fox's current contract with Major League Baseball's World Series, every episode since has aired in November, with the exception of "Treehouse of Horror XX", which aired on October 18, 2009.

From "Treehouse of Horror" to "Treehouse of Horror XIII", all three segments were written by different writers. In some cases there was a fourth writer that wrote the opening and wraparound segments. For "Treehouse of Horror", there were even three different directors for the episode. However, starting with season fifteen's "Treehouse of Horror XIV", only one writer was credited as having written a Treehouse of Horror episode, and the trend has continued since.

As of 2019 there are 30 Treehouse of Horror episodes, with one airing every year. They are known for being more violent than an average Simpsons episode and contain several different trademarks, including the alien characters Kang and Kodos who have appeared in every episode. Quite often the segments will parody well-known films, books, radio shows, and television shows. The Twilight Zone has been parodied quite often and has been the inspiration for many segments. The 31st season made a Thanksgiving themed episode named "Thanksgiving of Horror".

Episodes 
Key
 In the # column:
 The first number refers to the order it aired during the entire series.
 The second number refers to the episode number within its season: for example, 706 would be the sixth episode of the seventh season.
 The production code refers to the code assigned to the episode by the production team. The first two characters refer to the season the episode was made for. The second season is 7Fxx, the third is 8Fxx and the fourth is 9Fxx. After that, the fifth season started with 1F and continued in order until season nine (which was 5F). Starting with season ten, the production codes started with AABF, with the first letter changing for each season (i.e. BABF, CABF, etc.) The number at the end of the code is the order in which that episode was produced during that production run.

Notes

References

Related pages
 List of The Simpsons episodes

Other websites 
 Official episode guide at the Fox website TheSimpsons.com. Retrieved on November 10, 2007
 Treehouse of Horror I, II, III, IV, V, VI, VII, VIII, IX, X, XI, XII, XIII, XIV, XV, XVI, XVII, XVIII
 Episode guide from Warren Martyn and Adrian Wood's book "I Can't Believe It's a Bigger and Better Updated Unofficial Simpsons Guide" on the BBC website. November 10, 2007
 Treehouse of Horror I, II , III, IV , V, VI , VII , VIII , IX 

 
Lists of animated television series episodes