[[caption-width-right:333:This is The Husk, one of the many nightmares you'll see in this game. Believe it or not, he's one of the ''less'' dangerous ones.]]
->We don't have high octane nightmare fuel on this one.
->Simply saying "ALL OF IT" will suffice.
-->-A troper on the discussion page.

Indeed, for a game whose basic premise is a mother trying to kill her son, ''The Binding of Isaac'' is pretty unsettling.

However, a lot of the game's horror can also count as TearJerker. Isaac is abused and destitute, always unloved, always hated, in a house with an overly religious -- and also homicidally, sociopathically insane -- mother who hears voices. Oh, and the gateway to the Underworld is underneath his house filled with undead or otherwise demonic abominations of all kinds, that also adds a little bit to it.

[[folder:Original and Wrath of the Lamb]]
* The designs for bosses in Wrath of the Lamb are horrifying, such as The Husk (pictured above). The new bosses seem to be the old ones... [[BackFromTheDead after you killed them]]. Most of them look absolutely horrible, but [[UrineTrouble Peep's]] (now known as The Bloat) looks the worst by far. He seems to have collapsed on the inside and [[EyeScream is bleeding from his eyesockets.]] [[http://i.imgur.com/JPGfDSm.jpg Here's the poster.]]
** That said, while the nightmares of his appearance will probably diminish sooner or later, The Bloat will likely continue to give you nightmares [[ThatOneBoss of a different kind...]]
* The freakin' trailer. If the enemies looked creepy in 2D, imagine how horrifying they are in 3D! Or, don't imagine anything and just see it for yourself... [[http://www.youtube.com/watch?v=9au_e0im0aM If you dare.]]
** The teaser for the remake is even worse - now everything is not only 3D, but creepy, rubbery puppets: [[http://www.youtube.com/watch?v=p22Sj-Zllwk Link Here]]. Their use of a photorealistic cat's head for Guppy's severed head is jarring and somehow adds a surreal edge to the horror.
** And now we have [[https://www.youtube.com/watch?v=1aBb0M8HRCQ&channel=nicalisinc the very NSFW release date trailer]] for Rebirth. Sweet dreams...
* [[IronicNurseryTune The tune that plays on the credits]] after [[spoiler:defeating the true form of Womb's / Utero's boss]]. [[WhamEpisode It comes as a great surprise]] because [[BGMOverride it replaces the BGM that usually plays on that sequence]]... And it's creepy as hell! Made worse by the fact that it's called "Jesus Loves Me." And some speculate that [[WildMassGuessing it's Isaac who sings it before]] [[spoiler:suffocating in the Chest!]]
** "Hush (Jesus Loves Uke)", the song that would've replaced it in ''Rebirth'' [[CutSong if not for ESRB rating concerns]], is arguably even worse.
* The Halloween update included a new level, Sheol. Which, to quote Wiki/TheOtherWiki, is: "The earliest conception of the afterlife in the Jewish scriptures. [[TheNothingAfterDeath A place of darkness to which all dead go, regardless of the moral choices made in life]], and where they are 'removed from the light of God'". You know, [[UpToEleven just in case this game wasn't dark enough!]]
** A Trailer for the Sheol update [[http://www.youtube.com/watch?v=jruTNX0U3tM has been released]], and yes, it is [[DealWithTheDevil exactly]] [[DemonHead as]] [[EyeScream horrific]] as you'd expect it to be.
* The secret boss of the Halloween update. [[spoiler:What appears to be the Headless Horseman, represented as a jawless rotted head charging about the screen while its body acts like the second phase of Pestilence.]]
* {{Satan}}, the TrueFinalBoss of Sheol simply ''smiles'' before fighting you. It's unnerving.
** What's worse is his nonsensical battle cries, which for the most part are distorted demonic speech that can't quite be understood... but other times, can be clearly discerned as Isaac's name. [[FridgeHorror Why does the Devil know Isaac by name?]]
*** It's actually Mom's lines, reversed. [[Film/InTheMouthOfMadness Which has certain implications...]]
* The fight against Mom, in particular her repeated calls of "Iiii-saac..."
** In "Rebirth," her voice sounds [[BroughtDownToNormal like a normal woman's voice]]. That makes it ''worse''.
* ??? / Bluebaby is implied to be [[spoiler:Isaac after having locked himself in a treasure chest during [[HeroicBSOD a psychotic episode]].]]
* Similarly: ??? / Bluebaby is speculated by fans to be [[spoiler:Isaac or one of his siblings that died before birth and as a result is [[http://en.wikipedia.org/wiki/Stillbirth stillborn]], hence the X'd out eyes and the blue appearance. "Blue baby" refers to the fact that it never took its first breath and is just a lifeless corpse roaming around, which is why he has soul hearts instead of regular health. ''He was never alive to have a beating heart in the first place...'']]
* The "shopkeeper", a dried-out, eyeless corpse hanging by his neck from a rope, which would imply he committed suicide.
** That sure still doesn't stop him from taking the pennies off you whenever you buy something. [[AFateWorseThanDeath Maybe he is unable to die altogether...]]
*** If that's true, then what about the times where he ''[[BodyHorror lacks a head]]?''
*** Additional ParanoiaFuel -- note the fact that when you fight Greed, he has a noose around his neck -- one of these cadaverous shopkeepers got so mad or bored that he cut himself down and now wants to kill his customers. Now think that any single one of those shopkeepers could be him before you enter...
*** Take note of where you fight him. In secret rooms... and in shops.
* Imagine your head being slowly transformed into a tumorous mass filled with flies, all while still conscious. You'll want to put those poor Mulligans and Hives out of their misery as quickly as possible.
** And The Wrath of the Lamb? [[spoiler:Has ''an upgrade that turns you into one.'']]
** Also from Wrath of the Lamb -- the ones that have bombs painfully wedged into their skull and forced to charge at the player. Just imagine it for a second -- imagine you got possessed and used as a completely unwilling ActionBomb.
* It is implied that a lot of the monsters are Isaac's lost siblings. How the hell did they end up so horribly disfigured and WHY are they there?
** Well, considering the things that appear [[spoiler:IN HIS MOTHER'S WOMB]] and in the general areas of the basement: maggots, mutated flies, what is most likely a nest of aggressive parasites, the devil, evil arcana, blood all over the place, Isaac's mother, the karaken, a daedric prince, and randomly appearing flames, it seems likely that Isaac was either the firstborn and other kids came after the problems, or Isaac is just as tough as the person who defeated a knife-wielding maniac with no weapons.
*** Considering the large amount of Devilish upgrades he gets, he might as well turn up to become TheAntichrist.
*** And when you fail to become TheAntichrist -- read: you die -- it's possible that Isaac turns into [[AndThenJohnWasAZombie one more of them.]]
*** But, amusingly enough, Isaac is capable of taking on multiple Devil upgrades and multiple [[LightEmUp Holy upgrades]]... [[YinYangBomb at the same time.]]
** WordOfGod is that the monsters aren't Isaac's siblings, but Isaac ''himself''. Somehow this is ''worse.''
* Not even the game's soundtrack is immune to NightmareFuel, even if it does often cross into CrowningMusicOfAwesome. But probably the biggest offender so far would have to be [[https://www.youtube.com/watch?v=JcBtmCW1_ss Apostate]]. If anything, this track just goes to show you [[NothingIsScarier how really alone you are.]] It also doesn't help that [[spoiler:this is the theme to [[BodyHorror Mom's]] [[WombLevel womb.]]]]
* Many of the items Isaac can collect are extremely useful, but many carry a high cost in BodyHorror or [[DealWithTheDevil life energy/soul.]] Some of the worst are actually the most useful:
** The Book Of Belial: Grants Isaac increased power when used at the cost of giving him an angry EyelessFace and upside down cross mark on his forehead. [[TearsOfBlood Oh, and his tears are turned into blood.]]
** Toothpicks: Isaac uses them to [[EyeScream prop open his eyes by sticking them under his eyelids.]] [[TearsOfBlood This also causes his tears to become bloody.]]
** The Parasite: An aggressive parasite gives Isaac a split shot effect by [[BodyHorror burrowing deep into the back of his skull.]] It also dyes his tears a [[NauseaFuel sickly orangish brown.]]
** Spirit Of The Night: Gives Isaac the power of flight and ghost tears by transforming him from a little boy into a [[NightmareFace demonic specter with pale white eyes.]] [[DealWithTheDevil It doesn't help that this is also a devil room item.]]
** Stem Cells: Increases Isaac's health by [[BodyHorror growing a (probably dead) fetus on the side of his face.]]
** Cancer: A trinket that makes Isaac cry harder (shoot tears faster)... [[ExactlyWhatItSaysOnTheTin because it gives him cancer!]]
*** This one probably diminishes over time thanks to the description (''Yay, cancer!'') and how Isaac can simply drop it... though it's still rather chilling.
** Ouija Board: Gives Isaac ghost tears, but makes his [[NightmareFace face deathly white with a twisted expression]] like it stole his soul or something...
*** The wiki even says ''"Makes Isaac's head look undead or soulless."''
** The Pinking Shears: This is a giant pair of scissors which, upon use, makes a horrific slashing noise and ''slices off your head'', which you then control, flying it around and crying as normal as your body walks around as a little ally NPC.
** 8 Inch Nails: ''Afterbirth'' item. Replaces Isaac's tears with nails, but Isaac now has nails in his eyes. Makes you wonder why he isn't dead AND how can he tell where he's going.
** And you can potentially make all of these worse if you consider the fact that often these effects stack with each other. So, watch as Isaac becomes a demon with toothpicks under his eyes and a dead fetus on his face!
* Most of the [[GameBreakingBug bugs]] of the game just fiddle with mook and boss behaviour, or lock you out of certain things. Some other bugs, however, are genuinely terrifying. One of the most persistent bugs happens after clearing a level, when, [[spoiler:after the game apparently freezing, replaces the bad dream intermission scene with a version completely in black and white, a la ''ComicBook/SinCity'']]. Guaranteed to make you defecate bricks the first time you see it. Even more disturbingly still, no one really knows if it is a bug, an intentional feature, or [[ThrowItIn both]].
** Glitched Isaac. Before it was fixed, it could pop up after blowing up a blue rock. It's a copy of Isaac, riding a pony, inside of a Book of Shadows's shield. It floated around the room, and its body contorted and spun at lighting speeds while [[ExorcistHead its head stared constantly at the camera]]. And besides that, it did [[NothingIsScarier absolutely nothing]].
* In many of the secret rooms that you either find randomly from an explosive enemy or through a power-up[[labelnote:*]]or, you know, intentionally by blowing your way into it[[/labelnote]], you'll find a single, desiccating corpse with a fly or two. In front of the corpse is sometimes a pile of coins, sometimes another power-up[[labelnote:*]]or a Slot Machine[[/labelnote]], but all the corpse does is sit there, rotting. Did he die from being walled up in Mom's basement? Is he the remains of one of Isaac's attempts at escape? What's worse, sometimes the corpse has no face.
** Since he looks similar to the shopkeeper (sans noose) and since you fight greed in the shops and in the secret rooms, the person sitting in the secret rooms is speculated to be the shopkeeper/greed, if not yet another version of Isaac himself.
** [[spoiler:From ''Afterbirth'', the dead shopkeeper/secret room body is confirmed to be Isaac, [[DrivenToSuicide who hung himself]] in a secret room after being trapped in there.]]
* There's a new boss in [[spoiler:The Womb/Utero]] called Teratoma. Wait, what does Teratoma me- [[http://en.wikipedia.org/wiki/Teratoma OH, SOMEONE TAKE IT AWAY!]]
** For those who don't want to follow the link, a teratoma is a tumor ''with teeth, eyes, arms, legs, and maybe even internal organs.'' Oh, and they're generally there from birth. [[spoiler:And the Teratoma is in the Womb...]]
*** Also? The Teratoma in Isaac is '''FILLED WITH SPIDERS.''' Think about that.
** Teratoma might be horrifying, but it's not even ''close'' to being the worst bit of BodyHorror that lends its name to something in the game. If you come across an unfamiliar term related to enemies or items, [[SchmuckBait it's probably something you]] ''[[YouDoNOTWantToKnow do not]]'' [[BrainBleach want to look up]] - ''especially'' if it's an item that does something horrible to Isaac when picked up.

* The advert for the "Rebirth" expansion serves up Nightmare fuel hand over fist, what with the distorted music, flashing staticky backgrounds, masked nude figures and reverb-y, demonic-sounding singing.
* The new song for Sheol... is [[https://www.youtube.com/watch?v=DbiblpG4lAs this.]] It is fucking '''''DEMONIC.'''''
* You thought Duress was bad enough? Well, try listening to it on [[https://youtu.be/nH25UniPSjg?t=58m31s SLOW FUCKING MOTION]].
** Although as one comment on that video pointed out, [[NightmareRetardant it becomes a lot less scary when you consider that it sounds rather like Satan is beat-boxing]].
** And then there's the slow-motion versions of Ascension (2:03:10) and Everlasting Hymn (1:16:45). The OminousLatinChanting goes right past "Ominous" into straight-up ''hellish''.
* Rebirth brings us this [[SarcasmMode beautiful thing]], [[spoiler:[[http://hydra-media.cursecdn.com/bindingofisaacrebirth.gamepedia.com/d/d4/The_Lamb_intro.png The Lamb.]]]] ''Just look at it!''
* From The Depths onward, occasionally you may hear Mom laughing from somewhere within the area. You'll then be assaulted by a pair of disembodied hands, presumably belonging to her, [[Franchise/TheLegendOfZelda Wallmaster]] style.
* The spinning disembodied heads in [[spoiler:the Womb]]. They're a ''crying face orbiting around a lump of meat that slowly edges towards you.''
* [[spoiler:Isaac transforming into a demon]] in the final ending sounds awesome, right? ''[[NightmareFuel It's]] [[DownerEnding not]]''. [[spoiler: And that breathing will haunt you for life...]]
* End 2 in ''Rebirth'' shows Isaac finding the Rubber Cement... [[spoiler:and then he turns to the camera, with his eyes a horrifying milky white, as a ScareChord plays]].
** Many of the endings in ''Rebirth'' are noticeably DarkerAndEdgier than they were in the first game: endings 3 and 5, like the ones in the first game, have [[spoiler:Isaac hanging himself and his mom's arm dragging him into the chest, respectively]], but we also have beauties like ending four [[spoiler:where Isaac obtains the Wire Coat Hanger, soon finding it lodged in his head]], ending 6 [[spoiler:which has the poor boy getting sick due to the Ipecac and blowing himself up when he barfs in the chest]], and ending 7 [[spoiler:in which he finds the "Experimental" Treatment, which leaves him horrifically disfigured and mutated]].
* In ''Rebirth'', the beginning of the fights with [[spoiler:Satan and Mega Satan]] are silent except for the blowing wind. For the former, you wait a couple of seconds before fighting [[spoiler:the Fallen]]. for the latter, you [[spoiler:walk to a star in the center of the room. At that point, it starts spinning into a pentagram, Satan's battle theme starts playing, and Mega Satan materializes out of nowhere.]]
* [[https://www.youtube.com/watch?v=sPJnV_AvyZg This track for the]] [[spoiler:Dark Room]].
* [[https://www.youtube.com/watch?v=R6jJ66kaY2Q Also the nauseating]] [[spoiler:Womb track]].

[[folder:Afterbirth and Afterbirth+]]
* From ''Afterbirth'', [[spoiler:Hush, the [[BonusBoss bonus boss]] found after beating Mom's Heart/It Lives in less than thirty minutes. Its first form looks like a [[BodyHorror decomposing]] Blue Baby/???. Defeating this form reveals the ''real'' Hush, a [[EldritchAbomination gigantic mass of blue flesh.]] It has bullet patterns unlike any other boss, able to [[RealityWarper wrap bullets]] [[WrapAround around the edges of the screen.]] And when you deplete its [[DamageSpongeBoss massive health pool]] and finally kill the damned thing, its [[http://images.akamai.steamusercontent.com/ugc/392171335661053452/462613A1FB9A174FCC6CCEC31D006E9699C72BB5/ face scorches into the ground.]]]]
** Just imagine having a good run. Noticing a new floor and walking in on a boss who looks and acts like Blue Baby....[[https://www.youtube.com/watch?v=Y2UqIiPDtys and then this music starts to play after you kill him as a face with an agonized expression starts rising out the floor....]]
** Then there's the unused [[spoiler:[[http://i.imgur.com/5YWLAlJ.png Skinless Hush]]]] sprites found in the game's files. Let's just say that it's probably a good thing they turned out to be a RedHerring.
* If you thought [[spoiler:The Womb]] was gross and creepy, wait until you see the new alternate version in ''Afterbirth'', [[spoiler:the Scarred Womb. It looks like someone took a chainsaw to the inside. The stage theme, while significantly less fleshy-sounding, [[https://ridiculon.bandcamp.com/track/cicatrix is still oppressively dark.]]]] And then there's the ''fourth'' variation, [[spoiler:??? (referred to by players as the Blue Womb) where the aforementioned Hush is fought. While the Scarred Womb was pretty gross, the Blue Womb is just...dead.]]
** Oh, and bonus points! [[spoiler:The Blue Womb has ''faces'' in the walls. ''Screaming faces.'']]
** [[https://www.youtube.com/watch?v=xQBqzXZ1oIE The music of the Blue Womb is probably one of the creepiest in the game.]] It sounds just so...deranged. You can hear crying and roars at one point. And it doesn't stop when you enter the shop or item rooms. The death has completely penetrated the entire area.
** Arguably the most terrifying part is that unlike most bosses in the game, there is NO explanation for [[spoiler:Hush]]. Most of the other final bosses are either clear demonic/satanic archetypes, like Satan, [[spoiler:the Lamb, and Mega Satan]], or else [[spoiler:variations of Isaac himself (Isaac, ???, It Lives)]]. [[spoiler:Hush]] is just...[[NothingIsScarier there]].
** Actually, there is one theory about what [[spoiler:Hush]] is, which makes it even more terrifying: [[spoiler:with its blue coloration and pained expression that looks like it's gasping, Hush might represent Isaac's ''death from suffocating inside the chest.'']]
*** Eventually, [[WordOfGod Edmund McMillen stated on his Twitter that]] [[spoiler: [[https://twitter.com/edmundmcmillen/status/922696151651860480 "Hush is what Isaac sees his fate/death as (that being Blue Baby/???), and fighting it as it grows closer."]]]]
* Ending 17. [[spoiler:Isaac's mother enters his room and finds his skeletal remains in the chest.]] AdultFear in its purest form. Then there's [[spoiler:Isaac's shadow turning into a demonic creature with red eyes and a SlasherSmile...]]
* [[https://www.youtube.com/watch?v=zCMQT9s2qBA The trailer for Afterbirth+.]] Jesus CHRIST. [[spoiler: It shows a far more polished 3d animation of Isaac in his decrepit room drawing a picture of Guppy. All is well...until he starts bleeding from his nose. As that happens, all hell breaks loose, quite literally: the walls crack and insects appear, dead souls come from below his bed and demons start taunting him. Desperate, [[HopeSpot he flees to his chest to hide inside...but the monsters open the chest and enter it to attack poor Isaac. All of it in first person]]]].
** As if that wasn't bad enough, depending on how much do you believe this trailer, [[FridgeHorror the final ending adds another layer of horror to what we see]]: [[spoiler: the monsters no doubt spawn from Isaac's insanity, but [[FridgeHorror what if he didn't actually try to commit suicide in the end? What if he was merely trying to escape his inner demons and they somehow got to him anyways]]]]?
* The ultimate boss from ''Afterbirth +'', [[spoiler:Delirium]]. It's almost certainly the hardest boss in the game, acting as a FinalExamBoss by [[spoiler:mimicking all the other bosses' forms and attacks]]. But it's made all the more unsettling because it constantly jutters around as though it were [[{{Undercrank}} undercranked]], and will [[spoiler:teleport and switch forms without warning]]. Add on an incredibly creepy theme, and the fact that [[spoiler:it's a manifestation of Isaac's own deteriorating mental state]], and you have the makings of a truly disturbing boss.
* While also housing the aformentioned boss, the final level, [[spoiler:The Void]] is truly, deeply unsettling thematically. While initially it might be an interesting effect seeing all of the rooms [[spoiler:keep spontaneously changing their appearances from floor to floor and occasionally even glitching to a different appearance mid-room]], think about what it means from Isaac's perspective. [[spoiler:This is his psyche breaking down into nothing as he dies. Where there was some coherence to his delusional journey before, it's all falling away, the rules of the world loosening as his sense of logic decays.]] It's hammered home especially hard if you happen to die anywhere in this zone, as his will reads "I was killed by this thing in some [[spoiler:''dying memory...'']]". Another part that makes this troubling is that, once the level is unlocked, you can gain access to it at total random when defeating any boss after Mom. While this can be seen as a nice (if ''[[SchmuckBait completely suicidal]]'') bonus, this gets even more horrifying connotations when you think on it. [[spoiler:Isaac has prematurely snapped and has began his rapid downward spiral.]] Incidentally, said entrance can open with absolutely no warning, which can throw you straight into the jaws of this level without meaning to if you're not careful. Finally, consider what the entrance to that level is -- instead of the Trapdoors, holes, or beams of light from other floors... [[spoiler:It's a portal. [[OhCrap The same kinds of portals that have been spewing out enemies earlier in the game.]] The whole time you've been playing and coming into contact with those portals, that's been Isaac teetering on the edges of his breakdown, fighting back and destroying this encroaching force of madness...which he will eventually succumb to.]]
* The (presumably) [[DownerEnding final ending]] of the series is both this and a massive TearJerker. Isaac's breath [[spoiler:speeding up and slowing down and slowly turning blue as he suffocates in the chest]] is already bad enough, it has a huge dose of AdultFear in that [[spoiler:Isaac believes himself to be a demon and committed suicide after his family broke up]]. A ''[[spoiler:young boy committing suicide]]'', no less. Perhaps the most haunting aspect is when the camera pans through a wall of photographs and drawings, which starts normal, until [[spoiler:Isaac begins to draw himself as a demon]] with his parents arguing in the background.
** In fact, all of the game turns into a massive example of FridgeHorror because of this ending. [[spoiler: Every single thing in Isaac's horrifying journey, the sicknesses, the tumors, the bullying from his peers, the injuries from items like the nine inch nails, the malformed "twins", the brothers and sisters, the demons, places like the womb or its twisted versions, ''his very mother being a lovecraftian monster''...[[AllJustADream all of it were part of Isaac's lunacy and self-hatred]]. Talk about KidsAreCruel]].
* In the Shop floor of Greed Mode (not to be confused with the regular shops seen throughout), some of the waves include harmless shopkeepers/secret room corpses that spawn alongside enemies. This would be par for the course of the game's creepiness, but it gets worse when one considers what it might represent: [[spoiler:As the gameplay is all-but confirmed to be a metaphor for Isaac's imagination as he gets closer and closer to death, and the Keeper (a playable shopkeeper) is the version of a deceased Isaac we see after Greed Mode, it could represent Isaac's mind throwing more and more corpses to remind him what is going to happen since he remains suffocating in his chest. In other words, as the Shop is pretty far in to a Greed Mode run, he's getting close to death by that point -- something that the shopkeepers growing in number around him could represent.]] Then there's the more obvious ParanoiaFuel: Imagine turning around in the middle of a room swarming with enemies, finding dead bodies of ''you'' that don't move or do anything, but definitely weren't there before and are slowly growing in number.
* The [[https://www.youtube.com/watch?v=YpW0eWMkdJw trailer]] for "The Forgotten" update. It shows [[spoiler: Isaac's mother burying his skeleton after finding him dead in the chest]]. While this isn't too creepy on its own (it's more {{Tearjerker}} territory), the background music, "Hush (Jesus Loves Uke)", makes it at least a little creepy... [[spoiler: And then in TheStinger, [[NotQuiteDead Isaac's/The Forgotten's skeletal hand bursts from his grave]], [[JumpScare without any warning.]]]]
* Also, did we forget to mention you may (or may not) occasionally hear [[spoiler: Isaac's mother]] yell her son's name whenever you clear Basement 1 as of the latest Booster Pack?