* AlternateCharacterInterpretation: in spades. The episodes [[InvokedTrope invoke]] this in order to trigger the murders in each segment. See IdiotBall in the main page.
* EnsembleDarkhorse: Some of the monsters such as Count Burns, Devil Flanders, and King Kong Homer. An unusual example is Krusty in vampire getup from ''Treehouse of Horror IX'' who, despite not really playing a role in the segment, has been seen in TreehouseOfHorror merchandise and media.
* FamilyUnfriendlyAesop: Ned teaches one to Bart, Lisa, Milhouse and Nelson about the seven deadly sins in ''Treehouse of Horror XVIII''.
* HilariousInHindsight: In one episode, Snowball 2 is brought back to life with occult. In the recent ArchieComics miniseries, Afterlife With Archie, an attempt to bring back Hot Dog starts up the zombie apocalypse.
* NightmareFuel: Some of the shorts are '''really''' scary such as ''[[ImAHumanitarian Nightmare Cafeteria]]'' and ''[[BlackComedy There's No Business Like Moe's Business]]'' for starters.
** The Gremlin's first appearance in ''Treehouse of Horror IV'' "Nightmare at 5 1/2 Feet" with green fur, a wide SlasherSmile and WideEyesAndShrunkenIrises.
** ''Treehouse of Horror III'' to ''Treehouse of Horror X'' featured several ''disturbing'' CouchGag sequences, including: the Simpsons family appearing as skeletons[[note]]Treehouse Of Horror III, also used as official promotional artwork for Treehouse Of Horror II[[/note]]; erupting from the ground as zombies[[note]]Treehouse Of Horror IV[[/note]]; mismatched Frankenstein-esque monsters [[note]]Treehouse Of Horror V; this one serves as a SelfParody to another CouchGag where normal Simpson family members have mismatched body parts, but while in that one they correct the mistakes, in this one they screw it up even more[[/note]]; open-eyed hanging victims ([[RefugeInAudacity with Maggie still sucking her pacifier]])[[note]]Treehouse Of Horror VI; this one comes ''right after'' a HeadlessHorseman Krusty throws his own head at the screen, with the resulting blood splatter spelling out the title card[[/note]]; TheGrimReaper sitting on the couch, and the family members dropping dead one after another (and on each other) as they rush to the couch[[note]] Treehouse Of Horror VII; here, after this happens, the reaper [[RefugeInAudacity leans his feet on Homer's corpse]][[/note]]; the family getting electrocuted to death by an [[RefugeInAudacity "electric couch"]][[note]]Treehouse Of Horror VIII[[/note]]; the family ''actually never making it to the living room'' due to [[{{Deconstruction}} screwing up the timing of the opening]][[note]]Treehouse Of Horror IX; it could be argued that Marge and Maggie don't actually die, but even then, they would find [[BolivianArmyEnding Freddy Krueger and Jason Voorhes waiting for them.]][[/note]]; and a GrandFinale of sorts for the couch gags with a ContinuityCavalcade[[note]]Treehouse Of Horror X; said cavalcade consisting of Homer-in-the-box (THOH II), Alien-Maggie (THOH IX), Half-TheFly Bart and Witch-Marge (both from THOH VIII) where the Alien Maggie incinerates the OddOneOut, Lisa "as an axe victim", as soon as the latter [[FridgeLogic questions what aliens have to do with Halloween]][[/note]].
* ScrewedByTheNetwork: Creator/{{Fox}} has been generally unable to schedule these episodes within the week before Halloween since buying the exclusive rights to the [[UsefulNotes/{{Baseball}} World Series]] in 2001.
** This was even lampshaded in one special when the episode aired passed the Halloween holiday with Kang and Kodos stating it was near Christmas time.
* UglyCute: The blue Gremlin at first... until the [[NightmareFuel ending.]]
* WereStillRelevantDammit: The post-SeasonalRot episodes ''stopped'' being scary and are instead just parodies of 'relatively new' movies and TV shows with ''FamilyGuy''-esque sociopathic humor.