* Hishigi. Between his TranquilFury, his NietzscheWannabe outlook, his [[UncannyValley experiments]] and [[spoiler: [[EyesDoNotBelongThere the Devil Eyes implanted in the left side of his body]]]], he qualifies as walking Nightmare Fuel.
** Just after Kyo's fight with Nobunaga, when Kyoshiro has taken over Kyo's body, Hishigi shows up to stop Kyo from attacking. He laments that they have caught him without his sword, and then makes a ''terrifying'' face.
** In their final battle, a few of the heroes' comments trivialize Fubuki's suffering. Hishigi does not take that well.
* The Devil Eyes in general, especially the fact that they are ''[[spoiler: [[YourDaysAreNumbered eating Hishigi alive]]]]'', and are capable of [[spoiler: taking over the minds of their hosts (demonstrated with Akari, and one of Hishigi's worst fears)]].
* Kyo's UnstoppableRage after Nobunaga almost fatally wounds Yuya.
* [[spoiler: Shindara's death. The lower half of his body is completely destroyed to the point that even his regeneration is useless.]]
* The rare breed children in Hishigi's lab swarming Sasuke and self-destructing, all talking about how he needs to die with them.
* A lot of the earlier fights in the series are gory to a T, especially since the main characters had no moral restraints back then
* The Demon Eyes, while they look cool on Kyo, do not look right on anyone else, invoking one hell of an UncannyValley effect - especially with the child experiment "failures", who look extremely off.
** The True Demon Eyes are completely red and really live up to the name
* The Former Crimson King, a tyrant with [[AGodAmI a god complex]] who is [[ObfuscatingStupidity much more dangerous than he appears]], the fact he forces {{Synchronization}} onto priestesses for his plans with heavily implied perverse undertones, not to mention his other crimes. And then there's the intimidation aura he does to Yuya of several hands groping her...
** [[spoiler: when Kyo is defeated by Kyoshiro, the king appears to invite him into a LotusEaterMachine to forget all of his worries... only to try to murder him, made much worse since Kyo is a young child in the subconscious.]]
* Chinmei, a "peace loving" psycho controls gravity, [[AndIMustScream who has gone reasonably mad having lived for millennia, resulting in losing all of his sanity]]. Oh he also has [[spoiler: [[RedEyesTakeWarning the True Demon Eyes]]]].