Considering the source material
and the fact that one of the main characters is a Humanoid Eldritch Abomination
- Chapter 15. ADAM wakes up. And the planet collectively shits itself in horror.
- In Chapter 18, a conversation between Uriel and Rei:
"Why do I get the feeling," he says, "That if we fraternized, I wouldn't be the man in the relationship?"
She raises and eyebrow, stares at him for a moment, and shrugs.
"That's not true," she says, "You'd be the man."
She smiles, showing teeth, and for a moment he swears her eyes glowed.
"I'd be the Rei."
- On a more serious note, there's the encounter with Unit 04 in the Dirac Sea. "Creepy" doesn't even begin to describe that brouhaha.
- Kyoko's nightmare in Chapter 23. The fact that this could very well happen at this point in the story is even worse.
- What Iruel turned Asuka's Lotus-Eater Machine dream into. Brrr. It gets more disturbing than that. ]Iruel's conversation with Shinji revealed that Iruel didn't do that to her. In his words: "I'm saving your girlfriend for last because, well, she can put herself through shades of Hell I couldn't think of."
- And then there's this line in chapter 49: Asuka recognizes the place, though. It was where that very bad date happened where they fed the guy to Rei. Word of God is that this is not meant to be taken literally...which really isn't all that comforting a thought.
- Zeruel. Just Zeruel. It's just the way he's presented in the story; everyone reacts with terror at his mere presence. The other Angels are frightened of him. If it came down to it, Zeruel said that he would face the berserk and enraged ADAM.
- Zeruel and Chapter 66. Even if it was All Just a Dream, what happens is simply horrifying.
- Unit-01's berserker mode, even more-so than in canon. Ichi isn't the one in control while it's active, Shinji is. This becomes especially disturbing when Unit 01 starts consuming the Raziel-possessed Unit 03 much like it did to Zeruel in canon, and it's revealed that Ichi — who has the mind and personality of a six year old girl — could vividly sense everything that was happening and was completely powerless to stop it in any way. After that it isn't surprising that she closed herself off to the world.
- Now ordinarily, one would consider Iruel still being alive an example of this. That is, until Arael comes along, and silences him with imagery so vivid it makes him scream in horror. This may seem less nightmarish than other examples...until you remember that Iruel is the Angel who mercilessly tortured the Eva pilots, taunting them and turning their simulations against them and turning their ideal worlds into such twisted nightmares as Asuka being vivisected for body parts, and who nearly drove most of them beyond the Despair Event Horizon before Mari rescued them. And Arael reduced this callous, heartless, utter bastard of an Angel to a shrieking wreck. In summation: Arael terrified the Angel of Terror.