Fate/Zero/Nightmare Fuel

As nightmare inducing as Fate Stay Night is, there are reasons why Fate/Zero is considered Darker and Edgier.

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• Joy to the world, the anime adaption of Fate/Zero gives us a very nice animated look at what Zouken put Sakura through when she was a child. It's absolutely, utterly horrifying and disgusting. If you don't have a fear of bugs and (specifically) worms, you will after this scene. To fellow tropers who haven't yet seen it: a shower right afterwards is helpful, possibly necessary. Zouken, you will burn in hell for this...
• Again from the Fate/Zero anime, Ryunosuke Uryu and Caster's introduction is full of nightmare-inducing images. It doesn't help that both of them are completely and totally immoral and insane.
• Sola torturing Kayneth might not be as extreme as all the other examples mentioned here, but boy is it both creepy and nightmarish.
  • Probably because there are no Eldritch Abominations, serial killers, or other supernatural aspects, just a paralyzed man who's lost his reason for existence (his magic) being emotionally manipulated - and then, when it doesn't work, physically mutilated with the threat of being reduced to a limbless husk - by the one person he cares for.
• Oh, and Caster's lab. Oh gods, Caster's lab. Think Kirei's basement from Fate/stay night, just with a lot more blood and a lot less purpose.
  • To clarify, his lab consists of the still alive bodies of men, women, and children carved up and turned into instruments, artwork, and furniture. Excuse me, I need a hug.
• Fate/Zero episode 10 has a very Slasher Movie feel. Ryunosuke being the villain and Rin being the focus character does not help one bit, even though you know Rin survives. Well, it's Nightmare Fuel up until Ryunosuke gets beaten down (no real magic talent) by a small, extremely magically-talented, girl. Then it's a Crowning Moment of Awesome for Rin. And then Rin nearly gets jumped by one of Caster's tentacle abominations, and Kariya gets to pull an awesome Big Damn Heroes moment.
• Just Berserker possessing a JASDF F-15J with the pilot still inside. Also includes said destruction at the hands of Lancer.
  • How about Caster's monster eating one of the planes with the pilot still in it?

Command: "Report, what do you see? Report!"
Pilot: "Eyes. So many eyes."

• Episode 16: There's something extremely unsettling about watching Lancer's complete meltdown as he dies with his honor completely crushed, raving madly at everyone present.
  • Those orange eyes pouring blood... There's nothing worse (or sadder) than seeing Lancer cursing the world with that expression...
  • If you want to take things a step further, there's what became of Kayneth and Sola seconds after that. Maybe not "scary" nightmare fuel, but it is... hauntingly tragic and heart breaking. Seriously. If NOTHING in episode 16 affected you in some sad way, then you are either dead inside or Kirei Kotomine.
• Episode 22: First, it is extremely unsettling to see Kirei snap at Irisviel because he can't stand an Artificial Human with genuine feelings, when he, a genuine human, can't feel nor comprehend real emotions...
  • Then ... your emotions are jarred between incomprehension with mild horror as "Irisviel" watches herself and a cluster of Einzbern homonculi piled up on top of each other, then feeling yourself go DAWWW over Ilya making an horrible nightmare of what might await her since Einzbern homonculi designed for the Grail War share a common consciousness... then further horror as this scene falls to black ashes, meaning Irisviel's mind is literally falling apart, before revealing once more the pile of clones all staring towards the screen with a broken and empty look... before Angra Mainyu takes over her image and thoroughly corrupts her appearance in a twisted, horrifying smile. This troper could not bring himself to re-open the video file for another ten minutes after witnessing that and failing his SANITY saving throw. Even when KNOWING what was awaiting. God damn nice job, ufotable.
    • And then, Irisviel having a full black makeup Evil Makeover and coming to a realization that... not only is she dead and "something" has taken over her mind, but if she is inside the Grail, then it means... the end is near. CREEPY SMILE IS CREEPY I WILL NEVER SLEEP AGAIN
    • This actually feels like a Shout-Out to "that scene" in Episode 23 of Neon Genesis Evangelion, only done better. Much "better", for very scary values of "better", since they actually made Irisviel completely out of the Uncanny Valley