Nightmare Fuel / Marvel Disk Wars: The Avengers

• Episode 2: While mostly just enjoying the chaos. The Green Goblin stops dead in his tracks when he spots Spider-Man, escorting Akira and the other kids to safety.
  Green Goblin: (now sporting a creepy Slasher Smile) Hello, Spidey.
• Episode 3: The fact that King Cobra appears excited when he's about to attack Akira.
  • The fact that Loki goes so far as to taunt Ed, an innocent child is rather unsettling.
  Ed: It's not over yet, there's still Captain America. It's never over while Cap's around.
  Loki: Good, you still have hope. That just makes it all the sweeter. If there's one thing I love. It's turning hope, to despair.
• Episode 6: Joel has shown to be Beware the Silly Ones by sitting on a fence grinning as Abomination attacks and possibly kills the guards who are trying to keep an eye on the kids to keep them safe. Then he let Hulk (who was brainwashed by Diablo) to go on a rampage even after securing the DISK at the airbase.
  • Then there's Loki, posing as a member of the World Security Council and preventing SHIELD from mobilizing, meaning he's got two extremely powerful organizations under his thumb. And now, he's passed the Super Registration Act, showing just how much power he has over the world's state of affairs.
• King Cobra stalking Edward and Jessica in the seventh episode comes off as rather terrifying.
  King Cobra: Those kids can't hide forever...
• Episode 9: While Thor is trying to interrogate the Celebrity Five. Hikaru appears and warns him that Loki is nearby. Only for "Hikaru" to suddenly attack Thor with some magic. Then Loki reveals that it was actually him in disguise. While Voluntary Shapeshifting has always been a favorite tactic of Loki, it's still a bit unnerving to see him use the trick in such a cruel way.
• Graviton gets one of these as well in episode 13.
• Episode 16 has Sabretooth, who goes on a rampage and nearly kills Rosetta, stating that he doesn't care who he attacks, even if they're allies. The only thing that stopped him from doing so was Okuma, who nevertheless appreciates Sabertooth's zeal for destruction and almost comes off as being just as scary.
  • By episode 17, Sabretooth becomes ever more extreme. When Manino sent some Destroyer-drone robots to assist him. Instead of being grateful, Sabertooth destroyed one of the robots. He even went so far as to attack Rosetta, apparently intent on killing her.
  Sabertooth: What do they think they're doing? I said NO INTERFERNCE!
• The reason for Cap freaking out on Chris in episode 19? Because he lost Bucky, his first Kid Sidekick in WWII, and Bucky probably wasn't much older than Chris. The thought that Cap has already seen a child/teen get killed once is terrifying enough. He has every right to be afraid of one of the children getting hurt because of how dangerous their job is.
  • Bucky's fate alone is Terrifying in Hindsight if you know what became of him in the comics and other Avenger's media. Had the series continued longer, this could've potentially been shown here as well.
  • Which is combined with Tear Jerker in the dub, where Chris and Bucky have the same voice actor.
• Episode 20: while also a heartbreaking moment. After everything that's already happened to her. Not to mention Ōkuma shooting his mouth off, calling Mutants freaks, that aren't human and should not be trusted. Noriko unleashes her powers in a fit of anger. What's frightening is that she nearly goes over the Despair Event Horizon, briefly considering a Kill All Humans attitude towards humans.
  Noriko: These people, they will never change. What's the point? WE SHOULD JUST DESTROY THEM ALL!
• Episode 23 has the appearance of the Red Skull and he has a complete Biocode. Also, the fact that the Avengers consider him terrifying speaks for itself.
  • How did he get it, you ask? He took them from the Celebrity Five. Try not to think about how.
• Episode 24: Watching poor Groot burned to a crisp. True, he gets better thanks to his powerful healing ability. Still, it's rather disturbing to watch. Also counts as a Tear Jerker.
• Episode 25: Fin Fang Foom setting fire to the S.H.I.E.L.D. Helicarrier. Star Lord's description of the creatures' flames is also pretty terrifying.
  Star Lord: Fire breath burns as hot as a solar flare and it melts anything, and everything.
• Episode 28: Not only is Red Skull's plan to basically, blow up the Earth horrifying. His cold description of the plan is extremely creepy as well.
  Red Skull: The Gaia Lines are as the "life blood" of the Earth. I wonder what would happen if we injected them with an explosive venom... (shows an image of the Earth, suddenly breaking up into large chunks)
  • When Thor and Wasp point out to Red Skull the obvious flaw in his plan. Mainly, that his victory will be a hollow one, due to the fact that he'll die too. The clearly deranged Red Skull explains that he simply doesn't care.
• Episode 30: Deadpool's healing being disabled and he openly discusses how he's okay with him dying in this case. This moment is even more Harsher in Hindsight if you know his whole backstory.
• Episode 31: Power Man's time-limit running out before he can get the Build-Up plate to Ed. Leaving the boy facing down Abomination, without any superheroes to protect him.
• Episode 32: Red Skull's possession of Hikaru via the Dimension Sphere. Red Skull is basically forcing Thor to kill his friends or he will have Hikaru kill them, and possibly kill the rest of the children as well, his brother included. Not only that, it's revealed that were it not for Thor saving his life, the unlimited power could prove too much for him to handle, causing him to to go insane and could even kill him. Plus, his scream when he puts a shard of the sphere into his heart and when Thor's bond with Hikaru purifies him shows it's probably a painful process as well.
  • On a minor note, after Red Skull attacks them using the destructive power of the Dimension Sphere. None of the S.H.I.E.L.D. agents escorting Hikaru and Thor are seen again...
• Episode 36: What's worse than Spider-Man getting possessed by the Venom symbiote? How about Venom-Possessed Hulk?
• Episode 37: While minor. Thor lampshading Ultron's Uncanny Valley nature as a humanoid robot. Also counts as a bit of foreshadowing...
  Thor: If you ask me, he's a little too human.
  • Akira nearly getting sucked into the unstable vortex created by the Dimensional portal device.
  • The fact that a young girl like Jessica is the first person Ultron attacks directly.
  • Ultron calmly explaining his plan to subjugate humanity, by eliminating 30% of the world's population.
• Episode 38: Watching Ultron pull off his old routine from the comics. Having managed to download his consciousness into S.H.I.L.E.D.'s computer mainframe. After his original body was destroyed.
• Episode 39: Two words, Omega Ultron. Worse, Ultron made several of them. Sending them to several countries all over the world.
• Episode 42: Baron Blood and his army of Vampire minions.
  • That, and seeing all the kids (save Akira) being turned into Baron Blood's mind-controlled slaves. The way Blade describes it, Baron Blood apparently doesn't even need to feed to survive. He just does so, for fun.
  Blade: Baron Blood and his family are the most infectious and vile of all the vampire clans. They take cruel twisted pleasure in turning the people you care about most. Into their own brainwashed monsters. They don't do it for the blood of their victim. You see, once a person has transformed to become one of them. He can never return to normal. The best you can do, is put them out of their misery.
• Episode 43: Just the fact that even Ōkuma finds the actions of Baron Blood and vampires in general reprehensible. Considering his respect for such vile villains as Sabertooth, that's saying something.
  • Blade's warning about the Dimension wormhole generator, especially when he points his vial of holy water at it. Causing the water to actually boil just before turning a sickly gray color.
  • The first appearance of Ronin. Which starts with Akira, who was alone in the lab. Suddenly hearing what sounds like his fathers' voice. So, when Akira activates the portal machine. A creepy looking man dressed in black appears and steals the Dimension Sphere. Though not before attacking Akira and badly wounding Iron Man.
• Episode 47, Tony explaining what happened to him when he encountered Loki and Dormammu in the Dark Dimension.
  Tony: It was a nightmarish experience. One that I'd prefer to forget...
  • Loki's sadistic gleefulness as he tortured Tony is rather disturbing.
• Episode 49: Dormammu's ultimatum to the people of Earth.
  Dormammu: There are only two options for you pitiful beings to choose from. Be consumed by darkness and vanish into the void, forever. Or offer me your souls, and join the denizens of the Dark Dimension.
  • While they turn out of have "only" been a vision. The images of decay and ruin in the city and locations all over the planet were extremely unsettling.
• Episode 51, just the idea of Loki infused with all of Dormammu's powers and abilities.