History NightmareFuel / Parasyte

* Kana's [[ImpaledWithExtremePrejudice death]] is tragic, but then the scene focuses to a distraught Shinichi -- who suddenly shifts into such an immense TranquilFury that ''[[HorrifyingTheHorror Migi]]'' is unnerved once he proceeds to utterly rip out another Parasyte's heart.

* Kana's [[ImpaledWithExtremePrejudice death]] is tragic, but then the scene focuses to a distraught Shinichi -- who suddenly shifts into such an immense TranquilFury that ''Migi'' is unnerved.

* The (in)famous scene in the first chapter where a parasite-controlled middle-aged man [[BodyHorror opens up his head]], revealing several eyeballs and a [[MoreTeethThanTheOsmondFamily multitude of fangs]], and then proceeds to [[OffWithHisHead bite his wife's head off]]. If that wasn't nasty enough, the anime puts it ''[[RRatedOpening at the very beginning of the first episode]]''. See for yourself to the right!!
** As if that weren't bad enough, that man had a daughter. The scene cuts away when we see him responding to her call from the other room.
** Heck, most any scene involving any parasite feeding is this.

* The very concept of the parasites is terrifying. It's like ''Film/InvasionOfTheBodySnatchers'', only a hundred times worse. Someone you know, love, and care about could become the host of one of these things and there's absolutely nothing you can do to stop one from taking over your body unless you're insanely lucky like Shinichi was. And then they'll go around in your loved one's body, killing and eating people -- including you and other people you care about.

* The very concept of the parasites is terrifying. It's like ''Film/InvasionOfTheBodySnatchers'', only a hundred times worse. Someone you know, love, and care about could become the host of one of these things and there's absolutely nothing you can do to stop one from taking over your body unless you're insanely lucky like Shinichi was. And then they'll go around in your loved one's body, killing and eating people--including you and other people you care about.

* The flashback scene to Uragami's crimes, and his own twisted philosophy.
** Some of these crimes are so graphic and effed up in the manga ''that the anime actually omits them from being seen''. One of them includes the all-over mutilation and sexual assault of a '''[[WouldHurtAChild CHILD]].'''
** Uragami himself, period. He's a serial killer, but goes past the sociopathic tendency of seeing nothing wrong with his actions. He knows he's killing people and knows it's wrong, but he kills people, anyway, because he ''enjoys'' it, it's ''fun'' for him. The parasytes may be horrible creatures who can cause [[BodyHorror horrible things]] to happen to their host body, but Uragami is [[HumansAreTheRealMonsters human]] and, hence, comes across as a much more realistic person that can (and likely does) exist and could be encountered.
* Tamiya/Tamura blithely stating her intention to [[EatsBabies eat her baby]] if she finds no use for it once it's born. Thank God HumanityIsInfectious.