Deals with the devil? Sounds like it should be creepy!
* In Chapter 31 when Ciel and Sebastian are at Baron Kelvin's mansion and are having [[DidWeJustHaveTeaWithCthulhu dinner]]. The "circus" show he has a few children put on isn't all that scary... Until we see a little girl on the tightrope fall and we're treated to a panel of her leg and a nice ''splat'' complete with blood squirts. Then we see two other children drag off her headless corpse, leaving a lovely, bloody trail behind. Or how about the child who was a lion tamer that's eaten right on stage? The fact that Baron Kelvin is laughing and applauding makes it all the more frightening. Then he acts surprised that Ciel doesn't like the "show" he had the untrained children put on special for him. It was a pretty disturbing chapter.
** Also, he wasn't just using the kidnapped children to perform in the circus [[spoiler: or turning them into ceramic doll parts]]. He kept more of them locked up underneath his manor, ''trying to recreate the torture Ciel underwent while he was a slave''.
** Thought the manga part was bad enough? Wait until you'll see the anime adaptation. You just have to hear Baron Kelvin's voice once to know he's not exactly sane.
* Near the end of Chapter 32, it seems as though Jumbo took care of Finnian, complete with a [[BoomHeadshot bloodied forehead]]. As soon as he stands back up from the impact, we were then treated with a creepy image of a [[DissonantSerenity smiling Finni]], [[http://www.mangareader.net/102-2045-36/kuroshitsuji/chapter-32.html still with a bleeding forehead.]]
** In the chapter after that, as the circus folk try to infiltrate the mansion, Peter and Wendy try to cut Finnian in half with wire... [[http://www.mangareader.net/102-2048-9/kuroshitsuji/chapter-33.html and Wendy takes a bullet through her head out of nowhere]]. This is our first look at Mey-Rin in her ColdSniper mode, and it's a bit of a shock.
* In the first episode of the anime, a businessman comes to Ciel's house for dinner. At some point, he excuses himself and goes to answer a phonecall. Apparently, he was trying to cheat Ciel or something, of course, our favourite demon butler hears this and decides to make him pay by driving the man insane with hallucinitions to the point where Sebastian ''locked him in an oven''. the calmness of his voice is chilling...
* Ciel's flashbacks. A crazed cult leader stabbing a child in front of you? Horrific. How about a doctor who uses children's bones in his prosthetics stabbing a child in front of you the same way the cult leader did? Really horrific. Ciel got physically sick when he saw the doctor do this.
** It's as bad in the anime, where there's no sign of Ciel having been stabbed, but it's implied by Angela that he may have been raped. The flashback in the 22nd episode is also pretty creepy, with a naked Ciel calmly walking (through some rather eerie white mist) ''on top of'' the piled up corpses of the cultists without any fear or hesitation in his eyes.
** "The book of circus" however gives us a LOT of Ciel's flashbacks, two are even in the opening clip. We even learn why the cultists wanted to summon a demon: [[spoiler: to get enough money to be rich for the rests of their lifes]]. Too bad Sebastian thought that Ciel was far more interesting as a contractor.
* Drossel Keinz living dolls are terrifying for people with Dollphobia. But also the fact that he himself is a doll is quite the Fuel itself. But the worst thing for Dollphobic is the puppet of Drossels "Master".
** For the few episodes he's in, Drossel is loaded with creepy. He decapitates someone on screen, uses jewelry to pick out his victims, and always has that CreepyMonotone along with the IronicNurseryRhyme. One noteable bit of terror is when he's talking with Elizabeth on picking a gift for Ciel before he comes to his decision, you get a close up of his face with Lizzy reflected in his eyes.
-->'''Drocell''': It's perfect. We'll give him ''[[PuppetPermutation you]]''.
* ''[[Manga/BlackButler Black Butler II]]'' also has its fair share of horror, but the one scene that tops everything occurs in episode 10. It begins with Hannah talking to Ciel and saying that she has something to show him. Perfectly pleasant, right? Then her mouth opens unnaturally wide to reveal [[BodyHorror this black abyss where the inside of a human mouth would be]]. The eye she stole from Alois Trancy is rooted in the back of her throat, and since Ciel's soul has been partially fused with Alois's at this point, he's basically staring at himself from inside her. Hannah watches calmly while Ciel suffers a [[FreakOut severe nervous breakdown]]. Also counts as ParanoiaFuel, since up to this point the episode made you believe that they were really going to hit it off as master and servant.
* That bit where Claude is brainwashing Ciel into thinking he's Alois. Rewriting his past.
* Episode 1 where Alois [[EyeScream stabs out Hannah's eye with his fingers]].
* Angela/Ash during the last two episodes of season one. ''"[[MadnessMantra Every one...every one...every one, every one, every one, every one, every SINGLE LAST ONE OF THEM BE CONSUMED BY HELLFIRE.]]"''
** complete with nightmarish computer glitch-like transition between Angela's face and Ash's face. Oh man. And this troper thought only the When They Cry series could get that creepy...
* Ciel's LaughingMad moment at the end of the Circus arc in the manga is terrifying, especially considering how reserved he generally tries to be. After a massive PTSD attack in Kelvin's mansion and [[spoiler: arguably crossing the MoralEventHorizon by burning down the entire mansion with uncountable innocent kidnapped children inside]], discovering it was AllForNothing makes him... laugh, and laugh, and laugh, and babble about how humans are revolting and desperate and "[[HumansAreTheRealMonsters even more demonic than a demon]]", and how he's the same. And as the ribbon off his hat is stolen by the wind, you remember that [[TearJerker this is a thirteen-year-old kid]]....
* Any time the [[OurZombiesAreDifferent bizarre dolls]] show up. Especially [[spoiler: when they start acting more human- and begin repeating the same lines over and over.]]
* The werewolf curse. First you cry, then you get rashes, your nose starts bleeding uncontrollably, your face swells up, until eventually you die in agony.[[spoiler: Even more terrifying when we learn that the "curse" is actually the effect of inhaling a toxic gas, made by the villagers. And Siegliende was needed only for completing a formula for making the gas even more deadly]].
* The story of how [[spoiler: the P4 killed Derrick.]] First of all, [[spoiler: [[AdultFear his death is covered up and his family thinks he's still alive for a full year after his death.]]]] Then he gets turned into a zombie[[spoiler: - a semi-intelligent one who can still move normally for a few seconds before it starts eating humans.]] Finally, there's what [[spoiler: Derrick himself was dong to deserve his death. Torturing other kids along with his friends, and he even says they do so just to [[ColdBloodedTorture "let off some steam."]]]]
* We never get to see Sebastian's demon form in full. Judging by his mostly-offscreen NoHoldsBarredBeatdown of Ash/Angela, [[NothingIsScarier what he looks like and is capable of doing is probably pretty damn vicious]].
* [[WhamEpisode Chapter 94.]] The second half. [[spoiler: Sebastian finally snaps. However, it was probably just an act as we see in Chapter 95 (though Sebastian did say he was 90% serious about it...and probably ''would've gone through with it'' if Ciel hadn't snapped out of his BSOD right then and there.)]]
* Mr Phelps' sudden close-up during the conclusion of the ''Mystery Murder Mansion Arc'' [[spoiler: when Sebastian relates how he heard the snake and checked in the room, Phelps was begging for help and foaming at the mouth]].
* During the ''Campania Arc'', just the faces of the Zombies/Bizarre Dolls at times... especially unsettling how wide they open their mouths, if not weird movements like walking backwards or contorting themselves into weird shapes.
* In ''Book of Circus''[='s=] fourth episode, [[spoiler: we watch the circus members' abduction of a young girl, which seems to involve some sort of drugging or hypnosis (possibly by using MindControlMusic) that causes her to hallucinate. The police try to stop them, but are killed by the circus crew.]] What really makes the scene stand out is how [[spoiler: the girl sees the policemen as cute bears that "bleed" confetti. While the deaths we see for what they are are quite bloody, [[GoryDiscretionShot most of them are seen from the girl's point of view.]] It's quite unsettling to hear her laughing and clapping her hands in delight as the "bears" get offed]] and then happily entering the "Carriage to the Dreamland". It's even worse once you learn where the "Carriage" is actually going...
** Now we know that the poor girl was being [[spoiler: kept locked in the basement, in a perfect recreation of the cultist's room where Ciel was tortured. And in episode 9, Doctor used her for his lovely demonstration on how he extracted the material for his artificial body parts.]]
* Book of Circus episode eight: too many things to count. Let's just say that the episode is way bloodier and creepier than manga. Oh, and Grell is back.
* Book of Circus episode nine, [[spoiler: The last shot of Sebastian while he's engulfing the building in flames. He looks downright ''psychotic''.]]
* Grell's reaction to viewing Beast's death record (''and her "relation" to Sebastian'') can either be absolutely hilarious or absolutely disturbing.
* Doctor, after telling Sebastian and Ciel the whole story behind the children kidnapping, actually had a nerve to ask [[spoiler: Ciel of hiring him! Or recommending him to the Queen because "she's not getting any younger" and "could use some maintenance". To prove how brilliant he is, he made a lovely little demonstration on how he "extracted" the material needed to make artificial body parts.]] Ciel '''snapped'''.
* Chapter 97: The miasma that affected Ciel [[spoiler:is actually [[DeadlyGas a chemical weapon that kills anyone who breathes it in when it vaporizes.]]]] Think about that. [[spoiler:Humans created a chemical gas]] potent enough to affect a demon like '''Sebastian'''.
** Then again, chapter 99 gives a new nightmare moment for Sebastian. He actually suffers no ill effects from [[spoiler:the mustard gas]], as shown when he breathes in an entire room of the stuff and exhales it later.
* Sieglinde got her legs and feet [[spoiler: permanently broken and then tightly bound up]] as a part of "The Ritual" for the introduction of her as the new Green Witch. [[spoiler: The whole werewolf story was entirely made up by the villagers to trick Sieglinde into completing and then giving them the formula for a new chemical weapon, the "ritual" was just to keep her from suspecting anything or keep her from escaping if she ever found out the truth.]]
* The cliffhanger at Chapter 98: Ciel has an emotionally broken Sieglinde alone and [[spoiler: held at gunpoint, forcing her to choose between going out into the outside world (promising that she'll most likely "be used by countless people and experience even worse tragedies than what already happened") or just "get it over with".]] This is also right after [[spoiler: Wolfram was given the order to find Sieglinde and kill her even though it's obvious that he doesn't want to.]]
* Chapter 100 has [[spoiler: Wolfram believing to have found Sieglinde after defeating Bard and Snake, but it turns out that it's Ciel dressed up like her and he's about to shoot Wolfram point-blank]]. It gets worse and goes into TearJerker territory since this has an aura of AdultFear in that [[spoiler: Wolfram could have understandably assumed that Sieglinde was either long gone or dead at the time]].
** [[spoiler: Wolfram nearly shooting Ciel the next chapter also counts.]]
* The murder mystery arc ends with Ciel and Sebastian telling the young Arthur Conan Doyle exactly what happened: [[spoiler: Charles Gray was responsible for the murders, and they framed someone else anyway (he's a criminal for other reasons).]] When Arthur asks how Sebastian was capable with all of the things he did, Sebastian [[BrokenMasquerade tells Arthur the truth that he is a demon.]] And if Arthur ever tells anyone, they'll be sure to kill him. His last words "we're always watching" [[BeenThereShapedHistory haunt Arthur for the rest of his life and convinced him to continue writing.]] [[ItAmusedMe The only reason Sebastian did that was because Ciel liked his writing.]]
** The anime makes it worse by having Sebastian show Arthur [[EldritchAbomination his true form.]]