Rurouni Kenshin/Nightmare Fuel

• Just about everything that surrounds Jin-E. The man has his Knight of Cerebus title very well deserved, considering what he did to Kaoru and how he managed to bring out Kenshin's darkest side afloat. Aside from a Blood Knight, he is also a hypnotist. He subjected Kaoru to a nasty hypnotic trick which put her in a telepathic trance...that forced her whole body into muscular paralysis. This also includes the muscles that allow her to breathe. No wonder Kenshin TOTALLY cracked and went Battousai, as this girl who was under his protectorate and he was starting to fall in love with would die in a truly horrible and underserved manner unless he murdered Jin-E. Kaoru did break the trance in the very last moment, but it took her LOTS of effort. And then Jin-E killed himself.
• Also, anything in regards to Gein the Mad Artist as well as the details we have in regards to how he made the meat doll with Kaoru's looks. Eeeeeeeeeew.
• The Psychological Horror implications of Saitou going to the Kamiya dojo behind Kenshin's back brings out the Adult Fear card with incredible strength. Think about it: he could've killed everyone there easily if he wanted to, and Kenshin wouldn't have been able to do anything.
• Shishio's final meltdown. Both literally and figurately. The way he was screaming and clawing at his chest... ugh. And then he dies via burning alive. His body cannot take all the physical pressure of fighting Kenshin and he simply combusts. While he's bitterly laughing about his Karmic Death, and as Yumi's lifeless body burns as well.
• From the anime only, but still both heartbreaking and horrifying: Sayo and Shougo's common backstory. Specially three scenes: their father being Impaled with Extreme Prejudice in front of them , their Ill Girl mother being gunned down as the kids and their uncle Hyougo have to leave without her, and then the view of everyone in their Japanese Christian village being crucified.
• Soujiro's past. It was already bad enough that his stepsiblings abused the crap outta him for being an illegitimate child, but the scene in which he snaps and kills them all after they try to murder him and pin the blame on Shishio is genuinely terrifying, and specially in the anime due to the very effective animation and pacing.