Nightmare Fuel / Ben 10: Ultimate Alien

• Aggregor; the guy is probably one of the most competent villains in the whole series, maybe the whole franchise. He did nothing but win for most of his story arc, usually using the protagonists as pawns. And he was ready to absorb (which might as well be kill) five aliens in order to get their powers. Even worse, his final plan was to absorb a Celestiansapien child. This guy was in many ways similar to Kevin 11 in the Ben 10,000 future during the point when he returned back to being evil.
  • And when he is finally defeated, it's at the cost of Kevin's sanity, causing him to turn evil again and become even more Axe-Crazy than he already was in his youth. He starts with just chasing the people who caused him harm, initially just to beat them up, but then to kill them; by the finale episode, he's completely snapped, now craving for more energy and power, and starts attacking allies and enemies indiscriminately just to absorb their powers. He almost acts like a drug addict, and his chasing of Gwen starts to sound like creepy stalker much like Darkstar.
  • Not to mention the fact that Ben as Echo Echo only survived him by having one of his selves hidden. Ultimate Kevin genuinely thought he was killing Ben and didn't hesitate a second.
  • In response to all of this, we have one of Ben's most disturbing moments. Faced with seemingly no other choice, Ben tries to use Ultimate Echo Echo to kill Kevin before he can do more harm. Gwen says he'd promised to try it her way:
    Ben: Yeah. I lied.
• Zombozo shows up again, and while losing the source of his power has brought him down from "omnipotent god of Monster Clown-ness," he compensates by acting in a completely Axe-Crazy, Joker-esque way. When we meet him, he'd just come back from burying some henchmen who'd displeased him. He kidnaps Ben's mother and places her in a deadly trap so she would die gruesomely while Gwen was watching, and attempted to shoot at Ben with acid. Worse yet is how Gwen punishes him for attacking their loved ones- it scares him enough to return him to the stupor he was in after Ghostfreak spooked him. The scene shows us Zombozo screaming in despair, then cuts to a fast forward showing Gwen and Ben's mother waiting. When asked by Ben and Kevin what happened to Zombozo, she merely replies they "had an agreement".
  • In Omniverse, he returns, but he's only got one eye visible... which implies Gwen blinded him in that encounter.
• Inspector 13's really, really, really horrible Evil Laugh. Even Ben is creeped out.
• Captain Nemesis wasn't much more than a Silver age superhero parody turned evil in his first appearance; yet, you won't laugh at him anymore in his next appearance, where he gets to be the first character in the franchise to succeed in killing innocent human beings. Several times. With at least one body shown (though from behind). And this is supposed to be a kid's show?
  • Well, when you undergo plastic surgery via the hand of someone best described as an Igor Expy, there's bound to be a line that gets crossed... namely, Gwen catching the leftover scent of the man's blood in the operating room. We get a Gory Discretion Shot, of course, but the cast knew he'd gotten a back-alley surgery because there was just that much blood left over. (As for the good doctor? We find him in a freezer case, quite dead.) There are a lot more deaths kept offscreen.
• Pierce's death in "The Purge". It's greatly disturbing how coldly the Forever Knights execute him, and then there's his scream...
  • Adding to that, it's later revealed that the Forever Knights presumably did the same to other aliens living on Earth as well.
• In "Perfect Girlfriend", Elena turns into countless nanochips and goes into (transformed into Ultimate Echo Echo) Ben's mouth and straight to his lungs as if she was really willing to kill him...
• In “The Ultimate Sacrifice”, Ben is trapped inside the Ultimatrix with the Ultimate Aliens come to life. Somehow they've become sentient and believe that he is keeping them prisoner and using them as desired (which in reality is more up Albedo's alley since he created the Ultimatrix), and are not happy with it... and they believe Ben's death will free them. You're treated to a scene of a flaming pit where Ben is going to be tossed into to roast alive, as several of his alien forms stand around chanting "Burn! Burn! Burn!"
  • Think about it, it's almost the same situation with Ghostfreak, but worse. Six of his most powerful aliens, who all evolved to be combat based, want him to die. Funny thing is, Ultimate Wildmutt and Ultimate Way Big didn't show up in this episode (while Ultimate Wildmutt's reason for absence is unknown, Ben had yet to use Ultimate Way Big at this point), but if they DID, Ben would have been dead in a few seconds.
  • Ben spends a good chunk of the episode snapping between himself and the sentient Ultimate Humungosaur personality, enough for the two to hold a conversation, and for the Ultimate Humungosaur personality to attempt to strangle Ben. This even extends to when Ben is in human form.
  • How does the Sentient Ultimate Humungosaur personality first reveal itself? Take over mid-fight, deliver a particularly brutal beatdown to the opponent, and when Gwen protests that Ben's taking things too far, it roars "I'm not Ben!"
  • When Ben first wakes up inside the Ultimatrix, he thinks he's dead and has to try and convince himself that he might not be.
  Ben: I'm too young to die. And too famous, not to mention handsome and smart and talented. And charming, let's not forget that! But, if I am dead, chances are the place with the fiery red light is not where I wanna go!
  • How does Ben escape the Ultimatrix, along with the Sentient Ultimate Aliens? By willingly jumping into the pit, the Heroic Sacrifice causing the Ultimatrix to spare him along with releasing the Sentients.
    • Before doing so, Ben comes to the conclusion that he has to sacrifice his life, both due to his mindset that a hero would sacrifice themselves for the sake of others, and because of the Ultimates' belief that he's been holding them captive.
  • The entire situation with the Ultimate Aliens achieving sentience? Caused by a glitch in the Ultimatrix's systems. If it weren't for Kevin getting Azmuth to help with the situation and correct the faults, the situation could have happened again.
• "Night of the Living Nightmare" as a whole, especially the part with Hex suddenly appearing behind Ben on his car's backseat...
  • And then we have the final scene showing us Albedo's nightmare, where he is hiding, screaming bloody murder as all of Ben's aliens are advancing toward him...
  • The whole idea of the Cassiopeian Dream Eater is kind of scary. Imagine the most scared you've ever been during the worst dream you've ever had. Now imagine a creature that is capable of putting you back there, and keeping you there indefinitely. Ben and company had to call a Galvan doctor to Save the Villain because there's no way to remove the thing without your face/head going with it - and Galvans are the smartest race in the universe. That means if you ran into this thing in the wild, there would be absolutely nothing you or anyone would ever be able to do about it; Earth doesn't just not have the means to remove it, the human brain may be incapable of the smarts it takes to develop such a thing. Pretty much any And I Must Scream scenario is scary, but this one makes damn sure you're gonna be screaming. Forever.
• Dagon; his minions, the Lucubras, are weird demonic creatures with the ability to brainwash humans merely through physical contact. And they are just bugs compared to Dagon himself, whose debut saw him convert almost all human beings into his minions, defeat Ultimate Way Big and give a Family-Unfriendly Death to Sir George, by striking him with lightning, stripping him of his immortality and turning him to ashes.
• Simian is accidentally responsible for infecting his planet with Xenocytes- y'know, the nasty parasites who mutate anything they feed off of into a DNAlien? Just think of the DNAlien you've seen up until now, only as monkeys with four arms. Surreal and scary, huh?
• In "The Enemy of my Frenemy" Charmcaster performs genocide, sacrificing the souls of everyone and everything on Legerdomain just to resurrect her father Spellbinder. This includes KILLING Ben, Kevin and Gwen for a brief time! Making her the very first villain to do so. Needless to say? Spellbinder is absolutely horrified his daughter would even conceive doing this. If not for her father calling her out on this and having her undo it? That would've been it for Ben and the gang.