* CompleteMonster: [[AntagonistTitle It]], a.k.a. [[MonsterClown Pennywise the Dancing Clown]], is without question one of the most horrifying characters ever written. It awakens from its hibernation every three decades and proceeds to murder and devour the children of the town of [[TownWithADarkSecret Derry]], often using the avatar of a jovial clown named Pennywise to lure children into its clutches. It prides itself on using its shapeshifting and hallucinogenic powers to torment its victims, preying on their phobias and acquired fears and likening the cultivation of their terror to "salting the meat." From 1740 to 1743, It was responsible for the disappearance of three hundred Derry Township settlers. In 1957, It killed Bill's six-year-old brother, George, and drove [[TheBully Henry Bowers]] to madness, then killed Bowers' friends after they succeeded in luring the Losers' Club into the sewers. After waking up in 1984, It kills a man named Adrian Mellon before resuming its violent killing spree of children. It proceeds to manipulate Henry Bowers into trying to kill the Losers; drives Bill's wife, Audra, catatonic by exposing her to its deadlights; and manages to kill Eddie before its final defeat. Evil through and through, It enjoyed killing and eating thousands.
* CriticalResearchFailure:
** In the book, the producer of Audra's movie (being shot in England) is stated to have once bowled a century at cricket. "Century" in cricket terminology is an individual score of at least 100 runs, a significant landmark for a batsman. Bowling a century can be used ironically to refer to a bowler who gives up over 100 runs in an innings, but it's obviously not an achievement to brag about in that case.
** A scene in 1958 briefly references the landmark medical drama ''Ben Casey'', which started airing in 1961.
* EpilepticTrees: The Losers' contact with the Turtle is because at least some of them have the Shining. Especially since a teenage Dick Halloran makes a cameo.
* GeniusBonus: When the Losers go into the house on Neibolt Street to have their first confrontation with It as a group, Richie finds a bunch of [[AuthorPhobia rats]] with their tails tangled up together. This what is referred to as a [[http://en.wikipedia.org/wiki/Rat_king_%28folklore%29 rat king]], and it is considered a very bad omen.
* HarsherInHindsight:
** [[spoiler:"Tell Stan unless he's on his way to Derry, he's a dead man!"]]
** Also, [[spoiler:"Take it from me Spaghetti Man (Eddie), better dead than wed!"]]
** Pennywise himself becomes this or HilariousInHindsight depending on how you look at it: In 2016, a bunch of "Creepy Clowns" started showing up scare-pranking innocent pedestrians.
*** What's more is that the producers of [[Film/It2017 the remake]] wound up being MisBlamed for this, with many people believing it to be some form of ViralMarketing.
* HilariousInHindsight:
** The homophobic teens who appear to commit the first on-page murder of the book[[note]]they actually didn't, since It really killed the kid[[/note]] repeatedly profess their love of Music/JudasPriest. Rob Halford, the band's lead singer, came out in 1998.
** An InUniverse example: After reading one of Bill's early "horrorbooks" about werewolves, Patty Uris thinks: "Werewolves, shit. What did a man like that know about werewolves?" We find out what Bill knows about werewolves in Chapter 8.
** Fans of ''Series/MysteryScienceTheater3000'' will get a real kick out of Richie gushing over ''Film/IWasATeenageWerewolf'', and naming ''Film/TheCrawlingEye'' as the only movie that ever scared him , and Ben thinking of ''Film/BeginningOfTheEnd'' and ''Film/TheBlackScorpion'' at a loud insect noise (keep in mind the show hadn't even started at the time).
** One of Richie's gimmicks is [[ManOfAThousandVoices doing a lot of voice impressions]]. In [[Film/It1990 the first live-action adaptation]], he'd be played by a young Creator/SethGreen, who would go on to demonstrate an impressive vocal range in his adulthood.
** Pennywise noting that the Losers' resistance to it is a new thing that's happened [[Disney/{{Frozen}} "for the first time in forever."]]
* HoYay:
** [[spoiler:Henry and Patrick alone in the town dump...]]
** In the book, [[spoiler:Richie is the last person Eddie talks to, and Richie and kisses him goodbye after he dies.]] There's also several passages where Eddie's hero-worship of Bill is described as love, and on a couple of occasions Eddie muses that his younger self would have died for Big Bill.
** In the fourth Interlude, Mike chronicles that Claude Heroux loved Davey Hartwell and followed him into unionizing because he would have followed him anywhere.
* JerkassWoobie: Henry Bowers starts the book as a vicious bully and ends it as an AxCrazy psychopath. But it's hard not to feel for him when we see he was raised by an abusive racist, and then It starts warping his mind.
** Victor Criss was likewise far from a nice kid, but he had far more sense than Henry, and over the course of the book starts realizing how far gone his friend really is. There's even a hint that at one point he tried to talk to the Losers about leaving Henry's gang and joining them (though we don't actually see it depicted). But at the climax of the 1950s story, he and Belch follow Henry down into the sewers only to [[spoiler: get killed by It]] and it's implied that [[spoiler: It is temporarily brainwashing them to get them to go along with Henry]].
* MoralEventHorizon:
** It crosses the line when it kills and feasts on Bill's brother George Denbrough (who is only 6 years old), tearing his arm off. It has also probably done the same thing to God knows how many other children before him.
** Henry crosses this when he begins to carve his name into Ben's stomach with a switchblade, and eventually goes even further when he stole and [[ShootTheDog poisoned Mike's dog]] and just ForTheEvulz and gleefully rubbed it in Mike's face. In the movie, he also he tries to kill Stan before being interrupted by It.
** Patrick crosses it when he [[spoiler:smothers his baby brother, and that's not even mentioning his animals.]]
** Tom crosses it in the book when after abusing her for years he beats Beverly's friend Kay nearly to death until she reveals where Beverly went.
* NeverLiveItDown: The infamous sex scene in the book (you know the one)
* NightmareFuel: Take a listen to the audiobook for another fantastic performance, this time from Creator/StevenWeber (i.e. Jack Torrance from the miniseries of ''The Shining''). Some of his readings will give you goosebumps, in particular the scene where Beverly confronts the old woman, and his interpretation of Pennywise.
* NightmareRetardant: Throughout the book, It transforms into various licensed movie monsters. We see It become [[Film/CreatureFromTheBlackLagoon the Gillman]], [[Film/{{Frankenstein 1931}} Frankenstein's monster]], [[Film/{{Jaws}} Bruce]], [[Film/TheMummy1932 The Mummy]], and even [[Film/IWasATeenageWerewolf the Teenage Werewolf]]. Then Mike is frightened by Film/{{Rodan}}, causing Pennywise to take the form of... a lawyer-friendly, generic giant bird. Given Toho's draconian copyright policies, it's impossible not to get the impression that even It is scared of being sued.
* OneSceneWonder: [[TheSociopath Patrick Hockstetter]] only gets one fairly brief chapter from his POV, but God is it memorable.
* TheScrappy: Richie is this for some. Especially in Weber's narration, where his constant vocal imitations and responses from the other Losers of "Beep beep Richie!" begin to grate and wear thin pretty fast.
** Ironically, he would prove to be [[RescuedFromTheScrappyHeap the most popular member of the group]] in the [[Film/It2017 second film adaptation]].
* {{Squick}}: In the novel, the gang, drained of energy after their first encounter with It in Its lair in the sewers, re-power themselves by losing their virginity with Bev. Is it emotionally significant to the story? Yes, but it's still a bunch of ''under age children'' having sex one after the other in a sewer.
** There's also the scene where Beverly encounters an old woman who is It in disguise. See NightmareFuel for details.
** To say nothing of the [[ItMakesSenseInContext fart-lighting scene between Henry and Patrick.]]
* TheWoobie: Every one of the Losers qualifies, with the ''possible'' exception of Richie (as he has a good home life and he invites some of Henry & co.'s bullying by being unable to keep from making smartass comments to them).
** Poor, poor Dorsey Corcoran. And Georgie.
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