[[caption-width-right:320: [- [[NegativeContinuity These specials aren't canon.]] Remember that, [[MadnessMantra you'll repeat it to yourself quite a lot while you watch them]]. -] ]]

->''"Hello, everyone. You know, Halloween is a very strange holiday. Personally, I donít understand it. Kids worshiping ghosts, pretending to be devils. Things on TV that are ''completely'' inappropriate for young viewers. Things like the following half hour! Nothing seems to bother my kids, but tonight's show, which I totally wash my hands of, is really scary. So, if you have sensitive children, maybe you should tuck them into bed early tonight instead of writing us angry letters tomorrow. Thanks for your attention."''
-->-- '''Marge Simpson''', introducing the first ''Treehouse of Horror''.

These are ''WesternAnimation/TheSimpsons''[='=] special annual {{Halloween Episode}}s. Earlier installments have the onscreen title of ''The Simpsons Halloween Special''. Every season but the first one has had one.

The specials are anthologies of [[ThreeShorts three short stories]] with a {{horror}} theme (there are exceptions, though, simply for the sake of NegativeContinuity), all PlayedForLaughs. The first episode had a framing story of Bart, Lisa and Maggie telling scary stories in their [[ArtifactTitle treehouse]], hence the name. The next three had different framing stories, but from the fifth onward, they were cut because of time constraints and the fact that the writers couldn't think of any good framing devices for the stories.

Many of the tales feature {{Affectionate Parod|y}}ies of contemporary HorrorFilms. Others are inspired by more traditional horror -- there is even a DramaticReading of Creator/EdgarAllanPoe's "Literature/TheRaven" in the first "Treehouse" episode.

An annual ''Treehouse of Horror'' comic book is also published by Creator/BongoComics, and is ''considerably'' DarkerAndEdgier.
[[AC:Recap pages]]
# [[Recap/TheSimpsonsS2E3TreehouseOfHorror Treehouse of Horror]], featuring "Bad Dream House", "Hungry Are the Damned", and "The Raven".
# [[Recap/TheSimpsonsS3E7TreehouseOfHorrorII Treehouse of Horror II]], featuring "The Monkey's Paw", "The Bart Zone", and "If I Only Had a Brain".
# [[Recap/TheSimpsonsS4E5TreehouseOfHorrorIII Treehouse of Horror III]], featuring "Clown Without Pity", "King Homer", and "Dial "Z" for Zombies".
# [[Recap/TheSimpsonsS5E5TreehouseOfHorrorIV Treehouse of Horror IV]], featuring "The Devil and Homer Simpson", "Terror at 5½ Feet", and "Bart Simpson's Dracula".
# [[Recap/TheSimpsonsS6E6TreehouseOfHorrorV Treehouse of Horror V]], featuring "The Shinning", "Time and Punishment", and "Nightmare Cafeteria".
# [[Recap/TheSimpsonsS7E6TreehouseOfHorrorVI Treehouse of Horror VI]], featuring "Attack of the 50-Foot Eyesores", "Nightmare on Evergreen Terrace", and "Homer³".
# [[Recap/TheSimpsonsS8E1TreehouseOfHorrorVII Treehouse of Horror VII]], featuring "The Thing and I", "The Genesis Tub", and "Citizen Kang".
# [[Recap/TheSimpsonsS9E4TreehouseOfHorrorVIII Treehouse of Horror VIII]], featuring "The HΩmega Man", "Fly Vs. Fly", and "Easy-Bake Coven".
# [[Recap/TheSimpsonsS10E4TreehouseOfHorrorIX Treehouse of Horror IX]], featuring "Hell Toupée", "The Terror of Tiny Toon", and "Starship Poopers".
# [[Recap/TheSimpsonsS11E4TreehouseOfHorrorX Treehouse of Horror X]], featuring "I Know What You Diddily-Iddily-Did", "Desperately Xeeking Xena", and "Life's a Glitch, Then You Die".
# [[Recap/TheSimpsonsS12E1TreehouseOfHorrorXI Treehouse of Horror XI]], featuring "G-G-Ghost D-D-Dad", "Scary Tales Can Come True", and "The Night of the Dolphin".
# [[Recap/TheSimpsonsS13E1TreehouseOfHorrorXII Treehouse of Horror XII]], featuring "Hex and the City", "House of Whacks", and "Wiz Kids".
# [[Recap/TheSimpsonsS14E1TreehouseOfHorrorXIII Treehouse of Horror XIII]], featuring "Send in the Clones", "The Fright to Creep and Scare Harms", and "The Island of Dr. Hibbert".
# [[Recap/TheSimpsonsS15E1TreehouseOfHorrorXIV Treehouse of Horror XIV]], featuring "Reaper Madness", "Frinkenstein", and "Stop the World, I Want to Goof Off".
# [[Recap/TheSimpsonsS16E1TreehouseOfHorrorXV Treehouse of Horror XV]], featuring "The Ned Zone", "Four Beheadings and a Funeral", and "In the Belly of the Boss".
# [[Recap/TheSimpsonsS17E4TreehouseOfHorrorXVI Treehouse of Horror XVI]], featuring "B.I.: Bartificial Intelligence", "Survival of the Fattest", and "I've Grown a Costume on Your Face".
# [[Recap/TheSimpsonsS18E4TreehouseOfHorrorXVII Treehouse of Horror XVII]], featuring "Married to the Blob", "You Gotta Know When to Golem", and "The Day the Earth Looked Stupid".
# [[Recap/TheSimpsonsS19E5TreehouseOfHorrorXVIII Treehouse of Horror XVIII]], featuring "E.T., Go Home", "Mr. and Mrs. Simpson", and "Heck House".
# [[Recap/TheSimpsonsS20E4TreehouseOfHorrorXIX Treehouse of Horror XIX]], featuring "Untitled Robot Parody", "How to Get Ahead in Dead-Vertising", and "It's the Grand Pumpkin, Milhouse".
# [[Recap/TheSimpsonsS21E4TreehouseOfHorrorXX Treehouse of Horror XX]], featuring "Dial 'M' for Murder or Press # to Return to Main Menu", "Don't Have a Cow, Mankind", and "There's No Business Like Moe Business".
# [[Recap/TheSimpsonsS22E4TreehouseOfHorrorXXI Treehouse of Horror XXI]], featuring "War and Pieces", "Master and Cadaver", and "Tweenlight".
# [[Recap/TheSimpsonsS23E3TreehouseOfHorrorXXII Treehouse of Horror XXII]], featuring "The Diving Bell and Butterball", "Dial D for Diddily", and "In the Na'Vi".
# [[Recap/TheSimpsonsS24E2TreehouseOfHorrorXXIII Treehouse of Horror XXIII]], featuring "The Greatest Story Ever Holed", "Unnormal Activity", and "Bart & Homer's Excellent Adventure".
# [[Recap/TheSimpsonsS25E2TreehouseOfHorrorXXIV Treehouse of Horror XXIV]], featuring "Oh, the Places You'll D'oh", "Dead and Shoulders", and "Freaks No Geeks".
# [[Recap/TheSimpsonsS26E3TreehouseOfHorrorXXV Treehouse of Horror XXV]], featuring "School Is Hell", "A Clockwork Yellow", and "The Others".
# [[Recap/TheSimpsonsS27E5TreehouseOfHorrorXXVI Treehouse of Horror XXVI]], featuring "Wanted: Dead, Then Alive", "Homerzilla", and "Telepaths of Glory".
# [[Recap/TheSimpsonsS28E4TreehouseOfHorrorXXVII Treehouse of Horror XXVII]], [[MilestoneCelebration the 600th episode of the series]], featuring "Dry Hard", "BFF R.I.P", and "Moefinger".
# [[Recap/TheSimpsonsS29E4TreehouseOfHorrorXXVIII Treehouse of Horror XXVIII]], featuring "The Exor-Sis", "Cora-Lisa", and "MMM... Homer".
!!This series provides examples of:

* AbnormalLimbRotationRange: Done in "Treehouse of Horror XVI", in a {{parody}} of / ShoutOut to ''Film/TheExorcist''. A possessed Homer climbs on the wall and ceiling, and rotates his head around 180 degrees. When Marge says she'll call Mr. Burns that he can't go to work, he falls back on the bed in success, with his head still backwards.
** In "Treehouse Of Horror I", Maggie turns her head around 360 degrees while looking for a knife.
* ActorAllusion: The "Treehouse of Horror II" segment "Bart's Nightmare" parodies the episode "It's a Good Life" from ''Series/TheTwilightZone'', with Bart cast in the role the bratty, powerful child Anthony had in the original story. Creator/NancyCartwright previously appeared in the "It's a Good Life" segment from ''Film/TwilightZoneTheMovie'', playing a sister of Anthony who ends up [[HilariousInHindsight getting trapped in a cartoon.]]
* AdultsAreUseless: Invoked in "Treehouse of Horror V" where Bart and Lisa [[CassandraTruth tell Marge]] about the cannibalism going on in their school, Marge promptly dismisses them telling them that she cannot fight all their battles- and they should forcefully scold the teachers to ''not'' eat them. [[spoiler: It doesn't work.]]
* AesopCollateralDamage: Parodied in a "Treehouse of Horror" episode where the entire family suffered painful transformations all because Homer insulted a gypsy woman. All Homer had to do was [[CurseEscapeClause apologize]], and he would've resurrected his ''dead son'', but since none of the karma [[ItsAllAboutMe actually befalls him]], he doesn't learn anything.
* AlienInvasion: Some scenarios with Kang and Kodos involve one, although just how competent they are at it [[DependingOnTheWriter varies.]]
* AlternateReality: None of the scenarios are considered canon.
* AllJustADream: A few stories end with it being revealed to be a dream or fantasy of one of the characters. The "Treehouse of Horror II" stories were explicitly set-up as nightmares that Lisa, Bart, and Homer have as a result of eating too much Halloween candy. [[spoiler:Though Homer's leads into an [[TheEndOrIsIt Or Is It?]] moment.]]
** [[spoiler: It's possible that it was a dream within a dream.]]
** "Nightmare Cafeteria" from the fifth episode features this ending. [[CerebusEnding Only to take a further turn for the freaky shortly afterwards.]]
* AmbiguousCloneEnding: Averted in "Send in the Clones". The last of Homer's copies is surprisingly blunt when revealing the original was killed by Lisa's plan.
-->'''Marge''': Then the real Homer--!
-->'''Homer's Clone''': First over cliff.
* AnalProbing: The short "Citizen Kang" from [[HalloweenEpisode "Treehouse of Horror VII"]] saw Homer abducted by Kang and Kodos. Homer's reaction to this is to say, "I suppose you want to probe me. Well, you might as well get it over with" and immediately drop his pants and moon his alien captors. Kang and Kodos respond to this in shock horror, begging, "Stop! We have reached the limits of what rectal probing can teach us!"
* AnArmAndALeg: In the cold opening of "Treehouse of Horror XXII", Homer does this to ''most'' of his limbs [[spoiler:after his arm gets trapped under a boulder,]] in a direct parody of [[Film/OneHundredAndTwentySevenHours Aron Ralston's plight]]. This ends in total NightmareFuel...
* AndKnowingIsHalfTheBattle: In "Treehouse of Horror XVI":
--> '''Moe''': Okay, this concludes this year's Halloween show. We hope you had as much fun watching our show as the Koreans did animating it. But there's one group for whom every day is Halloween. I'm talking about adult illiterates. For them, trying to read the morning newspaper is more terrifying than any goblin, ghoul, spook or spirit.
--> '''Lenny''': So won't you please donate a children's book or something?
--> '''Dennis Rodman''': Together, we can make reading a slam dunk.
--> '''Moe''': Dennis Rodman, what are you doing here?
--> '''Dennis Rodman''': Working off a speeding ticket. Happy Halloween, everybody!
* AndThenJohnWasAZombie: A few stories end with the Simpsons family ''still'' stuck in their monster-forms.
* AndTheRest: In one "Treehouse of Horror" episode, Homer believes he's the last man alive and mourns each member of the "main" family and "all the rest", which includes the pets, Maggie and the TV.
* AnthropomorphicZigZag: In the "Treehouse of Horror XXIII" segment "The Greatest Story Ever Holed," Snowball II sits on a throne in human fashion with her legs stretched out on Ralph Wiggum's head. She is a NearlyNormalAnimal cat otherwise.
* AnyoneCanDie: PlayedForLaughs. It's mostly the supporting cast, however. The Simpsons family themselves mostly only die when the the plot needed them to. It's usually happening to [[TheChewToy Homer]]. ''Everyone else'' is fair game in TheTeaser, however.
* ApocalypseAnarchy:
** When Springfield is nuked by France, Homer danced naked in a church.
** In the [[MillenniumBug Y2K]] story, Homer didn't fix his computer and everything collapses: chaos ensues and widespread looting begins.
* ArmyOfTheAges: Bart uses a [=DeLorean=] time machine and changed history where Marge married Artie Ziff instead of Homer, and are rich. Homer tries to counter it with an army of Homers across history. They all get easily beaten up by Bart and Artie.
* ArsonMurderAndJaywalking: in "Hell Toupee", Snake is sentenced to the electric chair under the 'three strikes' law. The three strikes in question are [[BurnTheOrphanage torching an orphanage]], blowing up a bus full of nuns (it was self-defense), and smoking a cigarette in a no-smoking zone.
** The 'Bus full of Nuns' line was even the [[Administrivia/FormerTropeNamer original]] TropeNamer for this trope.
** From "If I Only Had a Brain", when Mr. Burns' robot collapses on him;
--->'''Mr. Burns''': "Every bone... shattered, Organs... leaking vial fluids, a slight headache, loss of appetite. Smithers, I'm going to die."
** Harry Shearer's name in many of the end credits is this, as he often forgoes a Halloween credit and just uses his real name.
* ArtifactTitle: Only the ''first'' episode takes place in a treehouse.
* ArtShift: The ''Series/MadMen'' title sequence to "How to Get Ahead in Dead-vertising" (part of "Treehouse of Horror XIX").
* {{Autocannibalism}}: 
** In one episode, Homer's head is turned into a donut. Homer being Homer, naturally keeps picking at it.
** Also, in TheTeaser spoofing ''Film/OneHundredAndTwentySevenHours'', he eats most of his limbs. He comments that he tastes good at one point.
** This is the premise of the "Treehouse of Horror XXVIII" segment "MMM...Homer."
* BecomingTheCostume: In "Treehouse of Horror XVI", a witch curses the townspeople into being whatever their costume is during a Halloween party.
* BewareTheNiceOnes: Ned Flanders turning evil ([[VillainWithGoodPublicity or being secretly already evil]]) is a frequent plot. So far he's been Satan (especially ironic since Ned is a devout Christian); a global dictator in an alternate timeline; a werewolf; Satan ''again''; and a WellIntentionedExtremist serial killer.
-->[[LampshadeHanging "It's always the one you least suspect."]]
* BewitchedAmphibians: In a parody of ''Franchise/HarryPotter'', students are expected to turn frogs (presumably of original frog descent) into princes. 
* BlackComedy: Also a main feature of many "TOH" shorts.
* BloodierAndGorier: Used to set the Halloween episodes apart from the usual episodes.
* BodyHorror: Often and usually PlayedForLaughs. One memorable example is "that fog that turns everybody inside out."
* BrainFood: The zombies in "Dial Z for Zombie" (part of "Treehouse of Horror III") crave delicious brains. Amusingly, they turn down Homer because apparently, he has no brains. He actually is offended by this and starts yelling at the zombies over it.
* BreakingAndBloodsucking: In the parody of ''Bram Stoker's Dracula''. Bart and his friends are flying outside Lisa's window, telling her the silly perks of being a vampire. Bart then tells her she has no choice, smashes through, and is about to bite her when Homer walks in and [[ComicallyMissingThePoint warns him about biting his sister]]. 
* CannibalLarder: The teachers at school are eating the kids, and they keep the kids locked in small cages - except for a few "free range children" which are in a pen outside.
* CanonDiscontinuity: Hugo's scene, Kang being Maggie's real father and everything else listed here.
** Oddly, clips from these episodes ''show up'' in ClipShow episodes.
* CantGetAwayWithNuthin: Homer in ''Treehouse of Horror XXII''. He sneaks off with the candy that he was supposed to put at a Candy for Troops Drop Off, but he sneaks off with it to a place called [[ExactlyWhatItSaysOnTheTin Candy Eating Peak]]. After a boulder falls on his arm and he eventually chews off his arm, it turns out that [[BehindTheBlack Bart, Lisa and Maggie replaced the candy with vegetables offscreen]] with this note: ''Enjoy your veggies, homeboy''
* CaptainObvious: In the "Hell Toupee" segment from ''Treehouse of Horror IX'':
-->'''Lisa''': Of course! Somehow Snake's hair is controlling Dad and making him-
-->'''Marge''': [[LampshadeHanging Oh, Lisa, everybody already figured that out a while ago.]]
* CensorDecoy: There's a Fox Network censor in the teaser for ''TOH VIII'', whose name happens to be [[MeaningfulName Fox Censor]]. The unintentional effect was that he became a ''literal'' censor decoy, as the folks doing the DVD commentary admit to a very violent opening act.
* ChildEater:
** In the "Nightmare Cafeteria" part of Treehouse of Horror V, Springfield Elementary is suffering from both overcrowding in detention and food budget cuts. To solve both problems, the faculty starts eating the children one by one and sending the kids to "detention" for even minor infractions to process them as cattle.
** The Salem Witch trial parody in another Halloween episode had Marge and her sisters, being witches for the act, take up the Flanders idea that they would eat children. They even ate a bunch of kids off-screen before they reached the Flanders.
* CloseEnoughTimeline: A story from ''Treehouse of Horror V'' ends with everything normal, except for people having long snake tongues. Homer [[TropeNamers names the trope]] by saying this line.
-->''"Eh, close enough."''
** A similar thing happens in ''Treehouse of Horror XIV'' when Lisa ends up changing the appearances of Homer, Marge, Bart and Maggie, eventually getting to a point where they're their normal selves, but they spin hula hoops around.
-->'''Homer''': Okay, that's good. Stop there.
* ComedicSociopathy: These specials take the show's more moderate BlackComedy and crank it UpToEleven, with the main cast regularly maiming and killing each other at whim for gags. Of course it's all reset by the next segment.
* ConsolationBackfire: In an episode, after an army of Homer clones destroys [[ButtMonkey Old Gil's]] farm, Old Gil sighs and says "At least I still have my health." Cue the Homers eating him alive. His skeleton is left behind to say "Awwww..."
* ContrivedClumsiness: Bart uses the "My finger slipped" excuse when Lisa's science experiment turns into a miniature civilization, and he keeps crushing buildings in it.
* CouchGag: The first few specials(3-10) featured a darker spin, such as the family being zombies, the family shown dead and hanging from nooses (with Maggie being barely alive enough to suck on her pacifier), or dropping dead in front of the Grim Reaper who was waiting for them on the couch... One time they didn't make it to the couch ''at all'' (which was for the best since [[Franchise/ANightmareOnElmStreet Freddy Krueger]] and [[Franchise/FridayThe13th Jason Voorhees]] were waiting on the couch for them).
* CoveredInMud: In a Treehouse of Horror episode parodying Creator/OrsonWelles' ''Radio/TheWarOfTheWorlds'' broadcast: Springfield is terrified of being invaded by Martians. Sideshow Mel tells everyone to take off their clothes and wallow in the mud. That way the Martians will leave them alone, not realizing that they're people.
* CreativeClosingCredits: "Treehouse of Horror V" has the Simpson family (who has been turned inside out by toxic gas) singing a Broadway-style song. In fact, nearly all of the "Treehouse of Horror" episodes have credit gags in the form of Halloween-ized staff names.
* CruelTwistEnding: Happened in a lot of older stories, such as ''Terror at 5 1/2 Feet'' ([[spoiler: Bart manages to keep the Gremlin from crashing the bus but gets institutionalized for his efforts, with the Gremlin coming back to torment him]]) and ''Bart Simpson's Dracula'' ([[spoiler: The Simpsons stake Count Burns in the heart but Marge turns out to be the head vampire and the family attacks the somehow still-human Lisa]]).
* CryingWolf: "The Day the Earth Looked Stupid" has the residents of Springfield listening to Creator/OrsonWelles' ''Radio/WarOfTheWorlds'' radio broadcast in 1938 and panicking. Then they learn it was only a hoax. ''Then'' Kang and Kodos launch a real invasion, reasoning correctly that the townspeople will dimiss it as ''another'' hoax.
* CurseCutShort: Lisa gets bitten in "Night of the Dolphin". 
--> Ow! Son of a -
** Also in "The Ned Zone"
-->'''Ned:''' OH YOU STUPID SON OF A -- ''(explosion)''
* DarkerAndEdgier: Because AnyoneCanDie here ([[TheyKilledKennyAgain more than once]]) for the sake of some good ol' gore.
** In particular, ''Treehouse of Horror IV'' and ''V'' fell into this, a conscious choice by (then) showrunner David Mirkin, who claimed that Halloween specials should be both scary and funny. Beginning with ''VI'', the first under Mirkin's successors [[WesternAnimation/MissionHill Bill Oakley and Josh Weinstein]], the specials, while still having gory moments, weren't quite as intense.
* DealWithTheDevil: In ''Treehouse of Horror IV,'' Homer sells his soul to Devil!Flanders for a donut.
** In ''Treehouse of Horror XXIII'', Marge made a deal with Devil!Moe back when she was a kid to give her favorite child to him in the next 30 years in exchange for leaving her sisters alone. However, when that day comes, Marge is too attached to them to let any of them go. Homer then offers a compromise...[[BiTheWay by doing a threesome with Devil!Moe and another devil.]]
* DeliberatelyMonochrome: The "King Homer" segment in "Treehouse of Horror III" (a parody of 1933 version of ''Film/{{King Kong|1933}}'') and the long segment ''Dial M For Murder or press # to Return to the Main Menu'' in ''Treehouse of Horror XX''. The first part of the "Homerzilla" segment in "Treehouse of Horror XXVI" is this as well, but it switches to color halfway through.
* DevilInPlainSight: Kodos ([[NamesToRunAwayFromReallyFast the Destroyer]]) in, ''E.T., Go Home".
* TheDollEpisode: In "Treehouse of Horror III", Homer gets Bart a cursed Krusty doll from a Chinese man's curio shop filled with cursed and weird objects from around the world.
** But it comes with a free frogurt![[note]]That's ''good''![[/note]]
** The frogurt is also cursed.[[note]]That's ''bad''.[[/note]]
** But you get your choice of topping![[note]]That's ''good!''[[/note]]
** The toppings contain potassium benzoate. [[note]]...[[spoiler:That's ''bad''.]][[/note]] [[note]]Can I go now?[[/note]]
*** And the doll [[spoiler:wasn't even cursed, despite coming from an occult curio shop run by a strange Chinese man. The doll had a "good/evil" switch on its back that someone flipped on "evil"]].
* DontExplainTheJoke: During the cold open to "Treehouse of Horror XVII":
--> '''Mr. Burns''': (as The Cryptkeeper) Hello, boils and ghouls! I am The Cryptkeeper, or should I say "master of scare-a-monies"!\\
'''Smithers''': Hahaha, priceless, sir. You made the word "ceremonies" frightening.\\
'''Mr. Burns''': I know what I did!
* DoubleSpeak: Parodied in an episode, where, in a ''Film/StrangersOnATrain'' parody, Bart and Lisa agree to "prank" each others' teachers and "ding-dong-ditch" them. Of course, by prank, Bart means kill, and by ding-dong-ditch, he means throw the ding-dong in a ditch.
* DownerEnding: A lot of TOH shorts have these.
* {{Dracula}}: He's the father of ''TOH XXI'''s Edmund.
** Burns of course parodies the [[Film/BramStokersDracula '92 version of him]] in ''Bart Simpson's Dracula''. Drac also shows up at the beginning of Treehouse of Horror XX (dressed up as Comicbook/IronMan at one point) with the wolfman, Frankenstein's monster and the mummy.
* DrivenToSuicide: Professor Frink and Marge in ''Treehouse of Horror XXI.'' Bart in ''Treehouse of Horror XII.'' 
* EarlyInstallmentWeirdness:
** The first TOH has three separate commentary tracks.
** Up until ''Treehouse of Horror XIV'', each segment was written by separate story writers.
** Also, the first four have framing stories told by the main characters.
* EatTheCamera: Done at the end of Bart's nightmare in ''Treehouse of Horror II'', when Bart wakes up screaming due to Homer ''kissing'' him in his dream, out of all things.
* EskimosArentReal: Homer does it in "Treehouse of Horror IV":
-->'''Homer:''' Lisa, vampires are make-believe, just like elves, gremlins, and Eskimos.
* EvilChef: Lunchlady Doris is usually a LethalChef at worst in the regular continuity, but in "Nightmare Cafeteria", she starts to cook the school's children on Skinner's orders and serving them to the staff.
* EvilLaugh: Kang and Kodos in various appearances. 
* EvilAllAlong: Marge does a pretty good job of concealing the revelations that she's both a witch, and the Head Vampire. See also BewareTheNiceOnes.
* EvilTeacher: In 'Nightmare Cafeteria', the third segment of the [[HalloweenEpisode Halloween special]] "Treehouse of Horror V", the faculty of Springfield Elementary become cannibals to solve the overcrowding of students in detention and food budget cuts.
* EvilTwin: Hugo [[spoiler:is a subversion. [[TwistEnding Bart turns out to be the evil twin]]]].
-->'''Bart''': Oh, don't look so shocked.
* ExplosiveDecompression: Bart and Homer by the end of "Life's a Glitch, Then You Die", as part of a GoryDiscretionShot; Bill Clinton and Bob Dole suffer a much more realistic version of this trope in "Citizen Kang".
* EyeShock:
** In "The Terror of Tiny Toon" (part of Treehouse of Horror IX) where Bart and Lisa are caught inside ''Itchy & Scratchy'''s show.
** Also seen at the beginning of "Nightmare on Evergreen Terrace" (part of Treehouse of Horror VI) when Bart first sees Willie in his dream.
* FalseReassurance:
** Parodied in "Treehouse of Horror V":
--->'''Principal Skinner:''' "I've got a ''gut'' feeling Uter's around here somewhere. In fact, isn't there a little Uter in all of us? In fact, you could say that we ''ate'' Uter, and he's in our stomachs right now! ...wait, [[VerbalBackspace scratch that one]]."
** In another tale, "Hell Toupée," Snake is [[AllCrimesAreEqual sent to the electric chair for smoking inside the Kwik-E-Mart]] (it was part of a "three-strikes" offense stipulation). After Snake's body has been burned, Homer buys Snake's hair and wears it as a wig to cover his baldness. What he didn't realize was that Snake's soul was still inside the wig, and once the wig was on the soul gained access to Homer's brain and overrode his personality, forcing Homer to take revenge on all the witnesses who got Snake sentenced to death - including Bart. Homer, finding the murdered bodies of Apu and Moe and not realizing that Snake was behind the killings (and, more to the point, that he is ''himself'' Snake when the wig is on), promises to protect Bart by boarding up the door to his room. "There," he reassures Bart, "now nobody can get in." Then Snake takes over his mind and he sneers: "Or out."
* FamousLastWords: AnyoneCanDie, so there's a lot of these. A partial list:
** Treehouse of Horror I:
*** "Life with the Simpsons... what choice do I have?"- The house from ''Bad Dream House''.
** Treehouse of Horror IV:
*** "Oh, dear Lord! It's some sort of hideous monster. Aw, isn't that cute, he's trying to claw my eyes out."- Ned Flanders, ''Terror at 5 1/2 Feet''.
*** "I know I really shouldn't... but when am I gonna be here again? WHEEEEEE-AAAAAAAAAH!"- Bart, ''Bart Simpson's Dracula'' (gets turned into a vampire directly afterwards).
*** "You're fired!"- Burns, ''Bart Simpson's Dracula''.
** Treehouse of Horror V:
*** "Is that the best you can do?"- Groundskeeper Willie, ''The Shinning''.
*** "You're still not in your own world, Homer! I can get you home, but you'll have to do exactly as I- [[KilledMidSentence augh]]!"- Groundskeeper Willie, ''Time and Punishment''.
*** "It's hard for me to clean this giant pot when you keep spilling meat tenderizer all over me. Oh great, now I gotta work in the dark."- Jimbo, ''Nightmare Cafeteria''.
*** "For how long?"- Uter, ''Nightmare Cafeteria''.
*** "Hold on, kids! I'm coming to rescue the lot of you! Argh! Oh, I'm bad at this."- Groundskeeper Willie, ''Nightmare Cafeteria''.
** Treehouse of Horror VI:
*** "I am the Wondrous Wizard of Latin! I am a dervish of declension and a conjurer of conjugation, with a million hit points and maximum charisma!"- Martin, ''Nightmare on Evergreen Terrace''.
*** "Iíll strike where ye kina protect them Ė in their dreams!"- Groundskeeper Willie, ''Nightmare on Evergreen Terrace''.
** Treehouse of Horror VIII:
*** "I bet I'll get blamed for this."- Mayor Quimby, ''The Homega Man''.
*** "But Aquaman, you cannot marry a woman without gills. You're from two different worlds! Oohh, I've wasted my life..."- Comic Book Guy, ''The Homega Man''
*** "We can all work together to build a Utopian society, free of violence, hate, and prejudice!"- Ned Flanders, ''The Homega Man''
** Treehouse of Horror X:
*** "Lucite hardening ... must end life in classic Lorne Greene pose from 'Battlestar Galactica'. Best ... death ... ever!"- The Collector/Comic Book Guy, ''Desperately Xeeking Xena''.
*** "Don't worry, Dad. We'll be dead in five minutes."- Bart, ''Life's a Glitch, Then You Die''.
*** "Not fast enough!" -Homer, ''Life's a Glitch, Then You Die''.
** Treehouse of Horror XXV:
*** "So. He likes ghosts better, eh? Fine! Might as well clean this while I'm killing myself." -Marge, ''The Others''.
*** "Mmm... I smell toast."- Homer, ''The Others''.
*** "Oh no! You're not leaving me to clean this up!"- Lisa, ''The Others''.
*** "Woohoo! I'm the last of the Simpsons!"- Bart, ''The Others''.
* FogOfDoom: "Treehouse of Horror V" ends with a fog entering the house and turning the Simpsons inside-out.
* ForgottenFramingDevice: "Treehouse of Horror III" and "Treehouse of Horror IV" end without returning to their frame stories.
* FramingDevice: Used for the first few episodes.
** The first "Treehouse of Horror" has Bart and Lisa exchanging spooky stories in their backyard treehouse while Homer eavesdrops.
** "Treehouse of Horror II" has Lisa, Bart and Homer experiencing {{Acid Reflux Nightmare}}s after eating too much Halloween candy.
** "Treehouse of Horror III" has the family throwing a Halloween party for the neighborhood kids, with scary stories once more being exchanged.
** "Treehouse of Horror IV" features a ''Series/NightGallery'' parody, with Bart showing viewers different paintings, each of which segues into a different horror story.
* FurryConfusion: Scratchy (the [[FourLegsGoodTwoLegsBetter bipedal]] FunnyAnimal cat) and Snowball II (the normal quadrupedal cat) show up together in "Treehouse of Horror IX" segment, "The Terror of Tiny Toon". The two cats are at [[SlidingScaleOfAnthropomorphism such differing levels of anthropomorphism]] that FurryConfusion ensues. As Scratchy is male and Snowball II is female, this also inverts HumanoidFemaleAnimal hard.
* GainaxEnding: On occasion such as ''Bart Simpson's Dracula'' where [[spoiler: the vampire family go to attack Lisa then suddenly do a parody of ''WesternAnimation/ACharlieBrownChristmas'']] and ''I've Grown a Costume on Your Face'' [[spoiler: where Maggie turns the whole town into pacifiers.]]
* GenreAnthology: Parodies of Series/NightGallery and other horror related TV shows were common.
* GodGuise: Happens to Lisa in one Treehouse of Horror episode. An accident with her science fair project creates a race of miniature people, who think she is God for stopping Bart from destroying them.
* {{Gorn}}: The annual "Treehouse of Horror" series has this in a many installments.
* GraveHumor: These were used as openers for the early ones; the last one to use them actually had a tombstone reading "Amusing Tombstones", signaling the retirement of the gag.
* GroinAttack: 
** In a Treehouse of Horror segment Professor Frink kills his father this way as the only organs he didn't have were testicles.
** In another Treehouse of Horror, when attempting to stake the Vampire-Burns, Homers nailed him in the crotch first, before Lisa corrected him.
* GypsyCurse: The premise of "Hex and the City" (part of "Treehouse of Horror XII").
* HalloweenEpisode: The annual "Treehouse of Horror" episodes, every year since 1990. The creators have mentioned that they actually wish they could stop doing these, or at least wish they could change the anthology format, but that it became such an iconic part of the show that they felt they had no choice but to continue. They're PlayedForLaughs... [[NightmareFuel most of the time.]]
** Oddly enough, due to the Fox network's commitment to televising baseball's World Series, few of the "Treehouse" episodes since 2000 have aired anywhere near Halloween itself. For most of the 2000s they were scheduled ''after'' Halloween, in November; since 2010 they've typically aired earlier in October.
* HarmfulToMinors: Happens to Bart and Lisa in TOH XX ''or'' TOH IIX...
* HeadlessHorseman: The opening segment of "Treehouse of Horror VI" shows Krusty the Klown in the persona of the Headless Horseman.
* HeroicSacrifice: Subverted when Apu holds off the [[Film/TwentyEightDaysLater zombies]]. The family leaves thinking he sacrificed himself, while Apu complains that they were supposed to wait for him to get back.
** In ''Treehouse of Horror XXI'', Homer lets the vampires suck on his blood (to save Lisa from becoming a vampire). [[spoiler: [[HoistByHisOwnPetard His blood was filled with bad cholestrol, which poisons them.]]]]
*** [[spoiler: Homer also tries to fly back to the house, but he ends up falling down and (possibly) also dies from falling from a great height.]]
* HesGotAWeapon: In one of the early episodes, Kang runs past in the background yelling, "He's got a board with a nail in it!" He's being pursued by Moe, who does indeed have a board with a nail in it.
** They were actually outmatched, seeing as [[ItMakesSenseInContext they had just conquered Earth with only a slingshot and a baseball bat, after the Earth completely disarmed]].
* HomeworldEvacuation: One episode has 2 ships to leave the earth with various stars. One goes to Mars, and the other to the Sun.
* IdiotBall: {{Justified|Trope}} in order to both tell these episodes from the main canon (which still has a lot of Idiot Ball, [[UpToEleven just not to this extent]]) and [[AnyoneCanDie rack up a big body count]] (with Groundskeeper Willie being [[TheyKilledKennyAgain this side of Kenny McCormick]] in the fifth special), which in turn also tells the halloween episodes apart from the canonical ones.
* IHaveAFamily: Parodied and subverted in "Treehouse of Horror VII", when Homer first meets Kang and Kodos:
--> '''Homer''': Don't hurt me! I have a wife and kids; eat ''them''!
* ImAHumanitarian: A number of the stories revolve around many people being ''eaten''. These include an episode where due to budget cuts and the rise in delinquent students, the staff decides to use the bad kids as a new food source.
* IncriminatingIndifference: Parodied in ''Treehouse of Horror X'', after Marge accidentally runs Ned Flanders over, resulting in his death. At his funeral, Homer warns the family that appearing too sad might seem suspicious, so they enter the wake with bright smiles.
* IronicEcho: When the cannibalistic staff of Springfield Elementary corner the Simpson kids.
-->'''Principal Skinner:''' I'm going to enjoy devouring you, Bart Simpson. I'll think I'll start, as you so often suggested, by eating your shorts.
* JoggersFindDeath
* JuryOfTheDamned: "Treehouse of Horror IV" ("The Devil and Homer Simpson" segment), when Homer sold his soul for a doughnut, included a jury consisting of John Wilkes Booth, Lizzie Borden, John Dillinger, Blackbeard, Benedict Arnold, [[ArsonMurderAndJaywalking the starting lineup of the]] [[OpposingSportsTeam 1976 Philadelphia Flyers]], and UsefulNotes/RichardNixon (who, at the time of the show's premiere, was still alive, making this dialogue a mix of FunnyAneurysmMoment and HilariousInHindsight):
-->'''Nixon:''' But I'm not dead yet! In fact, I just wrote an article for Redbook.
'''Satan (Flanders):''' Hey, listen, I did a favor for ''you''!
'''Nixon:''' ''(meekly)'' Yes, master.
* JustIgnoreIt: "Attack of the 50-Foot Eyesores."
* KillEmAll: If the fates of all Springfieldians are in the balance, guarantee their survival may be a crapshoot. [[TheEndOfTheWorldAsWeKnowIt "Life's A Glitch, Then You Die"]], [[StuffBlowingUp "The Ned Zone"]], [[NukeEm "The Homega Man"]], and [[HuntingTheMostDangerousGame "Survival of the Fattest"]] are shining examples.
* KillThePoor: In the [[HalloweenEpisode Treehouse Of Horror XVII]] short "Married To The Blob," Mayor Quimby and the town of Springfield reach a compromise with Homer, who has gained an insatiable appetite after becoming The Blob: They keep Homer inside a new "homeless shelter," and any vagrants who enter are immediately fed to him. In a very twisted way, this is effectively supposed to kill two birds with one stone.
** Homer, as the Grim Reaper, uses a bum to demonstrate reaping for Lisa's class on Career Day in TOH XIV.
* KingKongClimb: In "King Homer". (Predictably.)
** [[spoiler:He doesn't make it to the top, and falls down in exhaustion. Cut to the planes flying around the top of the tower, with the pilots looking confused.]]
* LeaningOnTheFourthWall: In ''Homer³'':
--> '''Homer:''' ''(trapped in a CGI world)'' Man, this place looks expensive. I feel like I'm wasting a fortune just standing here. ''({{beat}} -- he scratches himself)'' Well, better make the most of it. ''(burps)''
** In "Treehouse of Horror V", one of the tombstones from the opening sequence is for "Amusing Tombstones". This was the writers' way of showing that they were tired of coming up with ideas for humorous tombstone messages. Similar sequences had been used as introductions in all four previous "Treehouse of Horror" episodes, but have not been used since this episode.
* LighterAndSofter: Oddly enough, this does happen on occasion, like in ''Homer3'', "[[Literature/TheIslandOfDoctorMoreau The Island of Dr. Hibbert]]", and ''War and Pieces''.
** The Treehouse of Horror episodes as a whole starting with ''Treehouse of Horror XIV''.
* LightmareFuel: It goes without saying that these are {{Halloween Episode}}s of an animated comedy series.
* {{Lobotomy}}: In one alternate reality, Ned Flanders is an Overlord. Several people have a part of their brains removed and claim it feels good and they appear relaxed. Homer escaped.
* LogoJoke: The [[Creator/JamesLBrooks Gracie Films]] fanfare is played on a pipe organ and is preceded by a scream, though this isn't always the case[[note]]The first ''TOH'' featured the regular jingle, since the episode is considered canon. The pipe organ version was installed for ''II'', and the woman's scream came along in ''IV''. On two occasions, the logos weren't Halloween-related at all: in ''IV'', the jingle was done in the style of ''{{VideoGame/Myst}}''[=/=]Music/PhilipGlass, continuing on the closing credits theme, which was done the same way; in ''XIX'', the jingle was done in the style of "Linus and Lucy", AKA The {{Peanuts}} Theme. And sometimes, the woman's scream is placed by another sound effect, such as Regis Philbin screaming, "My eyes, my beautiful eyes!" in ''IX'', and sometimes, a scream from Homer is heard.[[/note]].
* LongTitle: One of the segments in the ''Treehouse of Horror #16'' comic book is, "I Screwed Up Big-Time and Unleashed the Glavin on an Unsuspecting World! ...I Totally Saved the Earth's Butt and Made the Glavin Cry Like a Little Wuss!"
* LosingYourHead: Homer in "Treehouse of Horror XVI"
* TheMaker: Lisa Simpson did a school science experiment which created microscopic 'life'. [[note]] It was done by putting a baby tooth into a bowl of soda, with Bart giving the tooth an electric shock from static cling.[[/note]]
* MayanDoomsday: The basis of ''XXIII''[='=]s cold opening. It turned out it happened because the Mayans sacrificed the wrong person (they intended to sacrifice their own Homer, but, thanks to their own [[HappilyMarried Marge]], their own Moe ended up sacrificed instead).
* MillenniumBug: Happens in the "Treehouse of Horror" X story "Life's a Glitch, then, You Die", on a DownerEnding, but this happened to [[NightmareFuel air in 1999]].
* MundaneWish: In the second [[HalloweenEpisode Treehouse of Horror]], Homer gets a [[Literature/TheMonkeysPaw monkey's paw]] good for four wishes. The first wish is used by Maggie, who wishes for a new pacifier. The second is used by Bart, who wishes for the Simpsons to be rich and famous. Third is Lisa, who wishes for World Peace. (Homer: "Lisa, that was very selfish of you!") After aliens TakeOverTheWorld because nobody knows how to fight back (due to the world peace thing), Homer decides to use the final wish by getting very specific so it [[LiteralGenie won't backfire]].
-->'''Homer:''' "I wish for a turkey sandwich, on rye bread, with lettuce and mustard, and, '''and''' I don't want any zombie turkeys, I don't want to turn into a turkey myself, and I don't want any other weird surprises. You got it?"
--->''[The monkey's paw closes its finger in understanding. A turkey sandwich materializes. Homer takes it.]''
-->'''Homer:''' "Hey!" ''*digs in*'' "Not bad. Nice, hot mustard. Good bread. The turkey's a little dry." ''*In realization*'' "The turkey's a little dry! Oh, foul, accursed thing! What demon from the depths of hell created thee!?"
* [[MusicalEpisode Musical Segment]]: "There's No Business Like Moe Business" in ''Treehouse of Horror XX''. Done as a MilestoneCelebration, which is given a LampshadeHanging at the end of the episode.
* NegativeContinuity: These episodes always take place out of the normal continuity of the show.
** They also always go back to normal by the next part. For example, there's ''Treehouse of Horror XV'', where Springfield is blown up by a core destruct button.
*** While these Halloween specials are non-canon, several other episodes are also this, most notably ''Simpsons Bible Stories'' (which ended with [[spoiler: the Rapture happening and the Simpsons descending into Hell]]).
* NextSundayAD: "Life's a Glitch, Then You Die" aired on Halloween of 1999, but took place two months after that point.
* NoEnding: Subverted in ''Homer3''. [[spoiler: Homer is trapped forever in the live action dimension, but he is happy when he finds a bakery that sells erotic cakes.]]
** Played straight with some of the framing devices for the stories as they end up having no resolution, such as the Halloween party in the third special.
* NothingExcitingEverHappensHere: Unless...[[note]]You were in a Treehouse of Horror episode...[[/note]]
* NothingIsScarier: Invoked in the re-telling of "The Raven" (when the protagonist finds "darkness there and nothing more" behind his chamber door) - only to be promptly dismissed.
-->'''Bart:''' Y'know what would've been scarier than nothing?\\
'''Lisa:''' What?\\
'''Bart:''' [[ComicallyMissingThePoint Anything!]]
* NotInTheFace: The "Treehouse of Horror XV" segment, "The Ned Zone", has Flanders seeing a future in which he kills Homer.
--> '''Lisa''': Well, you can't fight fate. But if you must shoot our father, please remember our family motto, "Not in the face."
* OminousFog: The short featuring werewolf-Flanders parodies the hell out of this trope. "Guess I forgot to put the fog lights in!" Also, the short song with the fog that turned people ''inside out'' featured some OminousFog.
* TheOperatorsMustBeCrazy: In "Treehouse of Horror III," Marge tries to let the toy company know a Krusty Doll is attempting to drown her husband as she speaks. She holds and gets a song about how much fun it is to be clown.
* OpiumDen: In "Four Beheadings and a Funeral" (part of ''Treehouse of Horror XV'').
* PaperThinDisguise: Kang and Kodos disguise themselves as newlyweds hitchhiking to "Earth's Capital" in the 6th one; their disguises are rather ridiculous.
* ParodyMagicSpell: In one episode, Bart reads a spell from a magic book that's basically a list of odd brand names and famous surnames.
* ParrotExposition: From XI's "Night of the Dolphin":
-->'''Kent Brockman:''' Our top story: killer dolphins.\\
'''Lisa:''' Killer dolphins?
* PortalDoor: Memorably in "Homer³":
-->'''Homer:''' [[LampshadeHanging It's like something out of]] [[Series/TheTwilightZone that twilighty show about that zone.]]
* ProphecyTwist: Ned thinks in ''The Ned Zone'' that he must avoid his scary vision about Homer, instead [[spoiler: he's forced to shoot Homer to stop him causing a nuclear meltdown-which then happens anyway]]. Also see, ForWantOfANail.
* PutOffTheirFood: Parodied in "Treehouse of Horror IX". In the "Starship Poopers" segment, Homer and Lisa lose their appetite after seeing Maggie's fang. Homer then suddenly grabs Lisa's food and exclaims, "Wait, mine came back."
* RealWorldEpisode: Homer goes through a mysterious portal behind the bookcase and ends up doing this at the end of the seventh-season "Treehouse of Horror VI."
* RunningGag: Each story in "Treehouse of Horror V" features Groundskeeper Willie getting killed with an axe to the back after saying he'll help.
--> '''Willie''' (In the final short) I'll save ya kids! *axed* DAH! [[LampshadeHanging Och... I'm bad at this.]]
** That makes [[RuleOfThree three]] deaths.
* SapientCetaceans: In one episode, dolphins invade the land and take over. They can speak English.
-->Snorky: ''[in high pitched voice]'' [[EloquentInMyNativeTongue Snorky ... talk ... man ...]] ''[clears throat and reverts to deep male voice]'' I'm sorry, let me start over. Eons ago, dolphins lived on the land. Then your ancestors drove us into the sea, where we suffered for millions of years. I, King Snorky, hereby banish all humans to the sea!
* SchmuckBait:
** In ''Bart Simpson's Dracula'', when Bart and Lisa are running up the stairs to escape Burn's vampire minions. Bart comes across a lever for a "Super Happy Fun Slide". He lampshades he knows its a trap, but figures what the hey and pulls it. Leading to him sliding back down into the vampire lair, getting captured, bitten and turned. Homer nearly does the same thing later in the episode, but Lisa stops him.
--->'''Bart''': I know I shouldn't, but when will I be here again?
** In another early Treehouse of Horror episode, the aliens' cookbook "How to Cook For Forty Humans" caused Lisa to think they were going to eat The Simpsons, first thinking the dust covered title was "How to Cook Humans" until Kang blew some dust off to reveal that it said "How to Cook For Humans" until Lisa blew more dust off revealing "How to Cook Forty Humans" before the final dust was blew off revealing its full title. Unfortunately, Lisa's distrust ruined their chances of being pampered by the alien civilization and they were returned to Earth.
* SdrawkcabAlias: In the credits of ''Treehouse of Horror VII, Dan Castellaneta's name is spelled backwards.
* TheSecretOfLongPorkPies: ''Treehouse of Horror XX'' features a play of Moe using Homer's blood as an ingredient in a delectable beer.
* SeeYouInHell:
** "I'll see you in Hell yet, Homer Simpson!" ("Treehouse of Horror IV", Flanders/Satan)
** "See you in Hell." "Still pushing that boulder?" "Uh-huh." ("Treehouse of Horror III", various zombies returning to their graves)
* SelfDeprecation: In one segment, D-list celebrities are going to get shot into the sun. Tom Arnold voices himself here and proves a good sport about it.
* SeveredHeadSports: Also happens on one of the "Treehouse of Horror" episodes, again with Moe as the victim of a Mayan sacrifice. His head rolls down the stairs and is used by kids as a soccer ball.
** Zombie Jimbo, Dolph and Kearney kick zombie Skinner's head around in TOH III. He can feel it, too.
* ShoutOut: See the ever so convenient WholePlotReference.
** At the end of "The Day the Earth Looked Stupid", the scene shows the ruins of Springfield while "I Don't Want To Set The World On Fire" by The Ink Spots plays. ''{{Videogame/Fallout}}'', anyone?
* SilenceYouFool: TOH VII segment, "Citizen Kang", has Kang (or is it Kodos?) say this trope, TOH VIII segment, "The HΩmega Man", has Mutant Sideshow Mel saying this trope (subverted in that Mel quickly follows with: "...You're talking too loud."), TOH X has Maggie(in a different voice) say this to Lisa in the episode's couch gag, and near the end of the TOH XI first segment, "G-G-Ghost D-D-Dad", has the devil say "Silence, Sinner!" to ghost Homer.
* SlidingScaleOfComedyAndHorror: Sure, THOH is BetterThanABareBulb, but then again, [[IndecisiveParody it never finds its home at any point of the sliding scale.]] Which, [[WordOfGod according to main THOH writer David X. Cohen]], is entirely the point: THOH episodes must be both scary as hell and funny as hell, at the same time.
* SmartPeopleKnowLatin: In the parody of ''Franchise/ANightmareOnElmStreet'', Nerd and TVGenius Martin is seen AsleepInClass dreaming about conjugating Latin verbs.
* SomethingCompletelyDifferent: Some recent "Treehouse of Horror" take a break from horror stories and focus on science-fiction or comic books, or [[UpToEleven fairy tales]], with a darker spin...
* SoundOff: The dolphin army in "Night of the Dolphin".
* SpaceWhaleAesop: Guns are the only way we can protect ourselves from cowboy zombies.
* SpecialEditionTitle: Featuring the requisite spooky imagery as well as a [[RearrangeTheSong Theremin-style arrangement of the theme music]].
* SpeechImpairedAnimal: Subverted in "Night of the Dolphin" -- when Snorky takes the podium and begins his speech, he at first speaks in a squeaky, stilted voice with YouNoTakeCandle dialect, but then he clears his throat and begins speaking more eloquantly.
* TakeMeInstead: 
** Homer offers himself to a zombie horde so that his family can escape. He's ultimately rejected, as he doesn't have a brain for the zombies to eat.
** Inverted in another episode: "Don't eat me! I have a wife and kids. Eat them!"
* TalkingWithSigns: Seen in "Nightmare on Evergreen Terrace" (part of Treehouse of Horror VI"): After seeing Groundskeeper Willie (playing the role of [[Franchise/ANightmareOnElmStreet Freddy Krueger]]) for the first time, Bart holds up a sign that reads: "Eep."
* TakeThat
** ''XXI'' contains one directed at the TabletopGame ''TabletopGame/MouseTrap'', in which a parody called "[[ParodyNames Mouse Catch]]" is referred to as "the game so lame no one's ever finished it".
** In ''VI'', when Homer tries to describe the dimension he's trapped in by asking "Did any of you see the movie ''Film/{{Tron}}''?" everyone in the room replies "no" -- with the exception of Chief Wiggum, who then immediately tries to backpedal and claim he hasn't seen it either. 
* TheTeaser: The first two and the fifth had homages to ''Film/{{Frankenstein 1931}}'', with Marge addressing the audience. These Cold Openings were common place after the framing stories were dropped, though each varies in length and characters.
** Most of the "Treehouse of Horror" specials feature this; in the earlier days, it was Marge or Homer [[ContentWarnings warning the audience that the episode in question is violent]], while later specials featured a quick Halloween-related skit before the opening sequence.
* ThirteenIsUnlucky: "Nightmare on Evergreen Terrace" begins "on the thirteenth hour of the thirteenth day of the thirteenth month", with a public meeting to discuss the misprinted calendars purchased by the town.
-->'''Homer:''' Lousy Smarch weather!
* TitleConfusion: As [[http://gosimpsonic.tumblr.com/post/101093458525/hothbitch-the-simpsons-treehouse-of-horror this collage]] shows, the first twelve episodes called this series ''The Simpsons Halloween Special''. The thirteenth episode changed it to ''The Simpsons Treehouse of Horror'', and afterwards just ''Treehouse of Horror''. As far as episode guides are concerned, however, it always has been ''Treehouse of Horror''.
* TooDumbToLive: Happens from time to time, such as Bart pulling the switch for the "Super Fun Happy Slide" leading right back to Count Burns' chamber, the entire US still voting for Kang or Kodos after Homer exposes them (poor Ross Perot), permitting them to take over the world, or Homer plunging to his death (with the rest of his clones) in a gorge, in an effort to catch enormous doughnuts.
* ToServeMan: Parodied and ZigZagged in "Hungry Are the Damned." The cookbook's title is revealed to be not ''How to Cook Humans'' but ''How to Cook for Forty Humans''. (Creator/MattGroening wanted the full title to end ''...and Then Eat Them'', but was outvoted.) Kang and Kodos, upset at Lisa's accusation, returns the Simpsons to Earth.
* TouchTelepathy: In an episode Ned spontaneously develops the ability to see a vision of how someone will die when touching them. 
* TransformationTrauma:
** Cat-Marge and Werewolf Flanders.
** And when the family turned inside-out from the strange, viral cloud that got into their home due to cheap weather stripping.
* TroublingUnchildlikeBehavior: Bart ''and'' Lisa in TOH XX...
* TheUnpronouncable: In the first ''Treehouse'' special, one of the aliens remarks that in order to pronounce his name correctly, he'd have to rip out their tongue.
* UnrealisticBlackHole: In Treehouse of Horror XXIII. The mini black hole created by the particle accelerator is actually way too big. A black hole with the mass of the Earth would only be about 1/3 of an inch in radius.
* VampireMonarch: In a parody of ''Film/BramStokersDracula'', in order to de-vampirize Bart they have to kill the head vampire. Lisa figures Burns must be it since he bit Bart. So the family sneak back into his castle and stake him. However...
--> '''Lisa''': (At the end of the end when the family reveals they're vampires) What?! No, we killed Mr. Burns!
-->'''Homer''': You have to kill the ''head'' vampire.
-->'''Lisa''': (Gasps and points) ''You're'' the head vampire?
-->'''Marge''': No, ''I'm'' the head vampire. (Laughs manically)
-->'''Lisa''': Mom?!
-->'''Marge''': Well I do have a life outside this house, you know.
* VillainProtagonist: Homer is often this.
* WackyCravings: In the 'In the Na'Vi' segment of "Treehouse of Horror XXII", Kang reveals that pregnancy is particularly difficult for females of his species as their planet has no pickles and their only ice cream is butterbrickle.
* WastefulWishing: In the monkey's paw segment of "Treehouse of Horror II", Homer uses his wish by asking for a turkey sandwich. He regrets it when he realizes the turkey's a little dry.
* WholePlotReference: Often Hitchock references, fairy-tales and classic ''[[Series/TheTwilightZone Twilight Zone]]'' episodes, also see ''Film/TwentyEightDaysLater''... There should be a whole list of [[ShoutOut Shout-Outs]] here...
* WingdingEyes:
** Parodied in the "Treehouse of Horror XV" segment "The Ned Zone": When Homer hears about Flanders's ability to predict peoples' deaths, his eyes turn into skulls, then dollar signs, then American flags and finally a dog chasing a cat before his normal pupils return.
** In the opening for "Treehouse of Horror XX," Homer gets the dead Xs version of this after [[ItMakesSenseInContext his head is torn off by the]] [[Franchise/UniversalHorror Universal Monsters']] [[ItMakesSenseInContext angry wives]] and lands in the punch bowl. The eyes make up the Roman numeral in the title afterward.
* WritingAroundTrademarks: This bit from ''Treehouse of Horror V''.
--> '''Willie''': You got the Shinning!\\
'''Bart''': You mean the [[Film/TheShining Shining]].\\
'''Willie''': Shh, you want to get sued?
* WrongGenreSavvy: Marge and Lisa, usually the OnlySaneMan in the series proper, often find their usual logic fails within the far more surreal situations of the specials. Lampshaded in "Attack of the 50 Foot Eyesores" when Marge's voice of reasoning only makes things worse:
-->'''Homer:''' Don't you get tired of being wrong all the time?
-->'''Marge:''' ''*glum*'' Sometimes.
* XCalledTheyWantTheirYBack: From ''Treehouse of Horror XX'':
-->'''Jimbo''': The classics called! They want their costumes back!
* YankTheDogsChain: The ending of ''XI'''s "G-G-Ghost D-D-Dad". With one minute left to perform a good deed in order to get into Heaven, Homer saves a baby from a runaway carriage. Unfortunately...
-->'''Homer:''' Did you see that?! I did the deed! Open up!\\
'''Saint Peter:''' Oh, I'm so sorry. I wasn't looking.\\
'''Homer:''' Hey, I thought you guys could see everything!\\
'''Saint Peter:''' No, you're thinking of SantaClaus.\\
'''Homer:''' Well, I'll be damned.\\
'''Saint Peter:''' I'm afraid so, yes.
* YouCantFightFate: In "The Ned Zone" from ''XV'', Ned gains the power to foresee peoples' deaths after being hit in the head with Homer's bowling ball, and has a vision of himself shooting Homer to death. He believes he's managed to stop this, only to have a vision of Homer self-destructing the power plant's core and destroying Springfield. In the process of stopping this second vision, he ends up causing the original vision to happen, but Homer still manages to blow up the plant anyway.
* YourBrainWontBeMuchOfAMeal: In "Treehouse of Horror III", a zombie horde clamoring for "Braaaains" inspects Homer's head, then abandon him in disgust. Most ridiculously, the zombie taps Homer on the head and a very hollow sound is heard before it moves along.
* YourHeadAsplode: In "Life's a Glitch, Then You Die" of "Treehouse of Horror X", Homer and Bart realize they're on a rocket that's heading into the sun with various celebrity has-beens. Rather than spend another five minutes with Rosie O'Donnell and Tom Arnold, they eject themselves into space, where their heads swell up as they give a blissful sigh of relief and then pop.
* YourMom: In "Starship Poopers" (part of "Treehouse of Horror IX"), Kang delivers one of these to Homer while on ''Series/TheJerrySpringerShow''.
--> '''Kang''': Well (bleep) hyperbolic parabaloid (bleep) yo mama!
* YourWorstNightmare: In a "Treehouse of Horror", Bart and Lisa, in a parody of ''Franchise/ANightmareOnElmStreet'', are being terrorized by Groundskeeper Willie in their dreams.
* ZombieApocalypse: Two Treehouse of Horror stories have this: one where Bart uses an occult spell book to try and reanimate Snowball I ("Dial Z for Zombies" in ''III'') and another where Krusty Burger's latest sandwich turns the people into "munchers" (cannibalistic zombies; "Don't Have a Cow, Mankind" in ''XX'').