RumikoTakahashi in this series has really demonstrated that she can create some very creepy and unsettling entities, ranging from BigCreepyCrawlies to [[RedEyesTakeWarning red-eyed]] [[HumanoidAbomination humanoid]] ones.
* Naraku's [[spoiler: true body during his weakened phase, which consist in a loathsome blob of Youkai body parts and flesh]]. He often has them fighting against each other so that he absorb the winner and he is not above GrandTheftMe if he's ever [[HoistByHisOwnPetard absorbed by one]] [[spoiler: As the Infant can testify]]. For this reason, he is full of LovecraftianSuperPower, full of CombatTentacles and other BodyHorror; which gets even worse once he becomes a full demon.
** He himself lets you fight your loved ones for the sheer enjoyment of CorruptTheCutie, and is capable of BreakingSpeech as well as MindRape to force even a saintly priest like Hakushin into giving into his fears and becoming a helper of essentially {{Satan}}.
** [[spoiler: Both his giant black spider form, [[BodyHorror making his face appear inside his body]] and red skinned demon form, all of which make his final battle very frightening.]]
** Even his incarnations are this, Goshinki is a red-eyed, purple, people-eating demon that is strong enough to [[spoiler: break the Tetsusaiga in one bite]] and ridiculously fast, but the worst part of him is his mind-reading capabilities, which he can use to drive you to despair by exploiting your inner weaknesses. Others including Kageromaru and Juromaru a parasite and his mindless brute brother, as well as The Infant capable of MindRape capable of causing Kagome into a HeroicBSOD. Even Musou, TheBlank who can steal your face, capable of absorbing demons and his eventual [[YouWillBeAssimilated fate]] is considered one.
* The Cursed Noh Mask, made from a sacred tree imbedded with a Sacred Jewel shard, that feeds on people to gain a body, a blackish one made of absorbed corpses. What makes it worse than most demons after the shards is that it was awoken in the present day by being near its presence. And it goes on a killing spree targeting firemen and policemen as well as driving a FIRE TRUCK into Kagome's house to get the Jewel. Oh and there's not any [[NoOntologicalInertia reverse of the damage it's done]] yup the people the mask has eaten are gone for good.
** Even worse in the manga: no, no more blob body: instead, you see the mask ''eating'' some youngsters... then coming back with a huge, fat body made from human flesh and full of limbs and faces. And then it can also chase Kagome almost everywhere, and even when partially broken, it can still move on and kill.
** Another cursed mask in the manga bites people's head off. '''Graphically'''. The chapter wasn't adapted into the anime for exactly that reason.
* The Soul Piper, while a peaceful yokai that helps dead children pass on, if one has a big enough grudge; its eyes open and the soul goes to hell. This almost happens to a one shot character called Mayu until Kagome saves her. What makes it worse that this girl's ghost died in Kagome's time, meaning it'll always exist, and who knows [[FridgeHorror how many children have been sent to hell by this thing]]. Though it is a case of GoodIsNotNice, as the yokai only drags you to hell if you've become an evil spirit.
** Then you remember that it's an amalgamation of dead children itself who honestly should have zero authority to serve as guide to the afterlife upon which you realize it's no better than the angry ghosts it's sending to hell...
* Sesshomaru's [[OneWingedAngel true form]]--a [[RedEyesTakeWarning red-eyed]] dog that is as big as a truck. While his regular form is graceful and {{Bishonen}}, his true form is rapid, beastly and constantly drooling acid. The first transformation into it prior the pink smoke is his face turning into a canine face complete with SlasherSmile.
* The Curse of the Ink episode, involved an artist who drew hellish demons in order to get what he wanted, but ends up suffering a FamilyUnfriendlyDeath when [[spoiler: he is aged to death]]
** In the manga, [[spoiler: The living Ink, attracted by the artist's blood, sever his arm and then proceed to devour and melt him like a blob monster.]]
* The entire Gatenmaru arc, showing far you can take HumansAreBastards and the SuperPoweredEvilSide to its extreme before it becomes disturbing, Gatenmaru is your [[ImAHumanitarian human eating]] racist moth demon who disguises himself as a human with red lipstick and pink overcoat. Normally this would be a campy villain, except for three things, one that he prefers to eat women alive through his tongue while tasting their despair, while draining them to a husk which disturbs every sane person who watches this; and two he has a disturbing fixation to show how helpless half demons are by sealing Inuyasha in a cocoon in order to have him watch helplessly as he ate the women alive as he mocked him. The third thing is his gang, who all kill an entire village willingly and are not even terrified by how their boss is actually a demon, in fact showed even more zeal in their cruelty after this reveal, made even more disturbing in that they were humans gleefully following a bloodthirsty demon. This leads to Inuyasha giving them all a swift KarmicDeath with his SuperPoweredEvilSide, who takes things too far as he begins to hunt down every last man in the group, even those running away.
* The Spider Heads, while their leader is a BodyHorror of interconnected limbs shaped like a web; more terrifying is their implications of [[YouWillBeAssimilated being devoured and turned into a Spider Head]].
* The Worm Demon from Jineji's debut, is BodyHorror-eque demon who sends its young to eat, which the villagers blamed Jineji for. Unfortunately, it is unaware of BewareTheNiceOnes as the GentleGiant tears it apart.
* The first picture of Sesshomaru obtaining Bakusaiga is, well, [[http://images3.wikia.nocookie.net/__cb20111119024626/inuyasha/es/images/f/f9/Nacimiento_Bakusaiga.png frightening]].
* The Snake demon of the Orochi clan who was desperate enough to bite a piece out of [[spoiler: Moryomaru's arm]]: as a result, said piece of flesh ''bursted'' from his orifices and then swallowed him up from the inside in a truly horrific manner.
* Not all scary things in {{Inuyasha}} can be just demons, when [[spoiler: Kohaku]] goes from shy to emotionless killer, a change so sudden that it takes both Kagome and the audience by surprise. Even more disturbing is the SadisticChoice of Naraku in that if [[spoiler: Kohaku remembers killing off his own family]] he'd likely GoMadFromTheRevelation and be DrivenToSuicide to escape the guilt. Naraku you bastard
* The Maker of the Shikon Jewel {{Filler}} involves a radical JekyllAndHyde involving a bull demon [[spoiler: who is actually a half demon priest who turns into a demon at night]], which is scary enough except the DissonantSerenity and subtle build-up to this is very shocking to say the least.
* Tokajin, [[CoolSword no, not Sesshomaru's sword]]; rather a man turned demon sage who feeds off of a man eating tree, nourished by men he has trained to become spiritually aware enough so he can kill them. That is scary enough, but the man himself, is a plump [[UncannyValley vaguely human]] creature, quite unlike the {{Bishonen}} and [[NightmareFuel down right terrifying]] in the series.
* The Priestess Eater, an EldritchAbomination of a demon that lures in priestesses with a little girl in order to swallow them with the cave that is its body. [[BodyHorror its main core is a brain mass with a single eye and several tentacles]].
* Tsubaki's demon wolf, looking even more deranged than Sesshomaru's true form.
* The silhouettes of some of the demons that possessed Onigumo to become Naraku are unsettling to look at in episode 71 of the original anime.
* The Nikosen, a tree monster that was once a hermit, capable of regenerating even if you cut off the head. For some reason thankfully, he's cut from the adaptation, especially with the HellishPupils he has.
* St. Hakushin, an undead priest with BlackEyesOfCrazy; his backstory explains that he allowed himself to be BuriedAlive only to hit the DespairEventHorizon as he realized that he didn't ''want'' to die and that all of the villagers were praying for his death. [[spoiler: The MoodWhiplash of Mt. Hakurei transforming from a peaceful mountain to a hellish peak of spikes]] does not help matters.
** To make this even better/worse, what's depicted in Saint Hakushin's backstory is the entirely real, historical practice known as [[http://en.wikipedia.org/wiki/Sokushinbutsu sokushinbutsu]] - now banned in Japan, for obvious reasons.
* When Sesshomaru smells blood and the scent of wolves on the air, and goes looking for the little girl who helped him - and finds her body lying on the woodland floor, face down and empty-eyed. Sure, Rin got better, but that doesn't change the fact that she was ''mauled to death by wolves.''
* The Village of Demon Women, sure the Salamander demon is very {{Narm}}y in her "water lipstick face" form until she returns to being a rotting salamander; but what she has the women do is very unnerving. She implants eggs to parasite off of them and have them skin men alive.
* Hoshiyomi in his RedEyesTakeWarning form, when he's taken to OmnicidalManiac levels of SanitySlippage, had he not been stopped by Inuyasha, he would've probably destroyed the entire world with his black hole.
* Princess Aibi's Fire Birds. For one thing, they're white pterodactyl like creatures that ignite at will and an alarming screech, not to mention her mother, Tekkei, who first appears as a realistic looking red eye, later revealing to be a threatening phoenix like creature.
** [[spoiler: Tekkei's FamilyUnfriendlyDeath when Naraku bursts out of her forehead with CombatTentacles]].
* Hosenki, a skull faced {{Youkai}} with GlowingEyelightsOfUndeath [[RedEyesTakeWarning of the red variety]] and a former friend of Inuyasha's father. While peaceful, he becomes legitimately threatening as the corrupt shard he carried slowly made him darker and more violent. His OneWingedAngel into a monster made of diamonds do not help matters.
* Zushinezumi, a rat demon who [[ImAHumanitarian eats humans]], as well as commands an infinite amount of man-eating mice; when Hakudoshi takes the rats from him, he uses it to eat entire villages. While it's terrifying by itself to be EatenAlive by rodents, they can also multiply whenever they're cut.
* Onigokuki, a demon slave trader who lures children with his flute to be sold to other demons. It's full of AdultFear of child kidnapping and the implications of slavery.
* Bone Demon and her father, the former disguises a beautiful woman, but in reality is a red eyed demon [[BodyHorror that can absorb the bones out of your body through her hand]] and her father is a red eyed demonic skeleton.
* Kao, the Flower Demon. Doesn't sound intimidating right? Turns out he puts people in a LotusEaterMachine that makes their eyes have TearsOfBlood.
* Hitomiko, a priestess killed by Naraku and brought BackFromTheDead to be his [[FangsAreEvil fanged]] puppet, which is scary enough, but then it's revealed that 15 years ago, he once suddenly to her as a little girl with the full intent to kill her just on the chance of being a threat. When that failed he reduced her friends to corpses and killed her master It's a rather jarring action coming from a [[ManipulativeBastard normally manipulative]] [[TheChessMaster chess master]] who only kills to further his ends.
* Just when [[spoiler: Naraku is finally defeated]], [[spoiler: The Sacred Jewel decides to seal off Kagome in a pitch black space and the demons that make up Magatsuhi, complete with VoiceOfTheLegion show to stop Inuyasha.]] It's makes for a rather creepy climax, complete with an eerie soundtrack playing in the background.