History NightmareFuel / Ben10

* Max is [[OOCIsSeriousBusiness completely absent of his usual grandfather traits]] when the titular mask of "The Ultimate Weapon" is unearthed, especially given it was one of the major goals of his entire Plumber career. He becomes an UnscruplousHero that isn't afraid to elbow an innocent security guard to the side instead of treating civilians with care, he tries ram Enoch and the Forever Knights off the road without a shred of mercy, and is such a hard-concentrated man on a mission that he risks endangering Ben and Gwen's lives before he finally comes to his senses.

[[quoteright:350:https://static.tvtropes.org/pmwiki/pub/images/screenshot_84_0.png]]
[[caption-width-right:350: "What's the matter, Ben? Aren't you glad to see me? Haven't you learned by now that nothing can stop me?!"]]

[[/folder]]

[[folder:Alien Force]]
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[[caption-width-right:350:DarkerAndEdgier indeed]]
* “Everybody Talks About The Weather”: let's talk about what happens to the victims frozen by [=DNAlien=] Freeze Guns. They are frozen in a bluish-grey metal substance that can remain solid at normal temperature yet keep its victims in hibernation at a sub-zero temperature. It also happens so quickly too with the victims barely having any time to react with only a scream of agony as they're hit before they're completely encased in metal. Basically, they are instantly frozen, in a substance that ''will not'' melt under normal circumstances, essentially turning them into living metal statues. Meaning, that the heroes could've remained frozen ''forever'' and [[TheBadGuysWin the villains would have won]] if not for both Swampfire (And Ben ''being'' Swampfire at the time) and Alan's extreme heat abilities allowing them to thaw everyone out. Just seeing people frozen this way can be very unnerving, to say the least. To make matter worse it's implied the victims [[AndIMustScream are still conscious!]]
** How it happens to the heroes is also worth mentioning. At first, they manage to defeat the first wave and begin discussing what the big plan is... [[SurprisinglyRealisticOutcome only for reinforcement to come hiding in the cornfield with the element of surprise]] to freeze all of them. It happens in a very horror-movie style with Swampfire being frozen out of nowhere with the rest following suit one by one until Alan is only left standing. Sheriff Mason tries to fight them off but it [[ZergRush quickly becomes futile.]]
** Just look at the picture of Gwen above, after being frozen by one of the Freeze Guns, for example. The way her eyes are open wide in fear, her mouth frozen in an eternal scream of agony, the way her hands are trying to reach out futilely for help... She could've been frozen like that ''forever''...
* "Kevin's Big Score": Vulkanus forcing Kevin to [[BodyHorror over-absorb a piece of Taydenite]] that he then gets his mooks ''to mine from Kevin's back.''
** Ben revealing he's been lurking in the shadows as Big Chill the entire time, waiting for a moment to get Kevin free. Even Kevin didn't know he was there,
-->'''Vulkanus:''' You're in a bad position to make demands.
-->'''Big Chill:''' He would be if he were alone.
** After seemingly knocking Big Chill out, Vulkanus lifts him up, only for Big Chill to suddenly lift up his head to Vulkanus' line of sight, sporting an unsettling grin that he doesn't usually sport... before surprise attacking the villain and freezing most of his body to the point that it ''shatters''. Thankfully, he doesn't die because he turns out to be a tiny alien in a robotic suit, but still... Big Chill smiled, and not in a happy way. The only other time he smiles in Alien Force is "Above and Beyond", seen below.
* The [[{{Mooks}} DNAliens]] are creepy on their own to an extent, but what can really be scary is the way they are created: the Hightbreeds use Face-Hugger-like creatures to infect humans, turning them gradually into these things. Which would mean each time the heroes kill [[{{Mooks}} DNAliens]], they are actually killing human beings (and it ''does'' happen);
** To make matters worse, they can disguise as humans through ID masks, so [[ParanoiaFuel they could be anywhere]].
* The episode introducing Darkstar was downright creepy. The episode starts with a scene of a schoolgirl running to a house and desperately calling at the door for help. The door opens, we get something that looks like a GoryDiscretionShot, and cut to the girl walking around in the street, now zombified.
** It's then revealed multiple girls suffered the same fate. As the protagonists try to figure out what happened with the help of what seems to be the local superhero, it's eventually revealed that this so-called "hero", despite possessing light powers, ''is'' the one responsible: he charges his powers by feeding off of energy from schoolgirls he seduces, eventually turning them into zombies slaves that he relies on to feed him even more. His habit of draining energy from them is played subtly like rape. To make matters worst, he succeeds in draining ''Gwen''.
** Speaking of draining, we get front-row seats to Darkstar flooring Kevin and Ben about five seconds into a fight. It plays out pretty much like ColdBloodedTorture, with the rapey vibes adding a whole other layer of creepy. Those ''noises'' Creator/YuriLowenthal made....
** And then his zombies slaves turn on him at the end, draining most of his energy and leaving him weakened with a zombified face. [[AssholeVictim Granted, he deserved it]], but that was still creepy.
* “The Gauntlet” has Cash, ordinarily a relatively harmless [[TheBully bully]], starting to use a Techadon hand as a gauntlet, using it as a toy initially. Then the gauntlet gradually takes over his body and mind, causing him to go way off the deep end and attempt to [[DisproportionateRetribution kill Ben as revenge for when Ben made him look ridiculous in front of his class]]. And then the gauntlet starts gradually rebuilding the Techadon around him, starting with his arm then covering his body then his head... he is saved eventually, but had the tech not been stopped, he would have probably been permanently mutated into a Techadon.
* The Highbreeds could be creepy on occasions, especially the one who was about to punish Simian at the end of his debut episode. Ben tricked Simian into carrying a [=DNAlien=] ear cleaner, which unlike human ears, need ''acid'' to flush out... and the Highbreed now has it in his possession:
-->'''Simian''': T... this is a horrible mistake!
-->'''Highbreed''': It sure is. We distinctly told you to bring the crystal. Maybe you misheard us. Maybe ''you'' need to have ''your'' ears cleaned... (loud hissing noises come from the acid dripping out the ear cleaner [[GoryDiscretionShot offscreen]] as the episode ends)
** An ''Ultimate Alien'' episode later retconned this scene so the Highbreed had just taken Simian to his ship rather than killed him. You read it right- the original ending was so creepy and dark the writers felt the need to retcon it.
* The first episode involving the Incurseans shows us Emperor Milleus disintegrating his own lieutnant ''on-screen'' because [[YouHaveFailedMe he failed to find and bring back his daughter.]]
* Zs'Skayr comes back, and now possesses some [[SarcasmMode lovely]] new powers. He is somehow able to produce a mass-possession all on his own, turning all the inhabitants of Vilgax's home planet into his minions as part of his HiveMind. The planet is then infested in a [[Franchise/{{Alien}} Xenomorphesque]] way, with cocoons all over the place. It gets so bad that Vilgax went so far as to ''ask Ben for help''.
** And then Zs'Skayr succeeds in what he had been trying to do for years: possessing Ben. Then he locks Ben's body in his own form, before trying to posses ''Vilgax''. He'd have gotten rid of both Vilgax and Ben by fusing them into his own being, and nearly succeeded too.
* Reinrassig III's debut- he had his arm ''severed'' by a desert parasite, complete with indigo AlienBlood dripping out. Luckily, Ben infused Swampfire's regenerative plant cells into the Highbreed's detached arm and reconnected it to his body- but even so, his arm became a hybrid of flesh and chlorophyll, turning it completely green, along with all the neighboring arteries and veins hooked into it where the chlorophyll eventually melded with the flesh. It's kinda cool-looking, but also scary.
** There's also those water-absorbing tentacles that pop out of his chest when he opens a few skin flaps on it- yecchh!!
* Highbreed Supreme is especially disturbing to look at- initially. Pale, [[FatBastard fat]], and with a face even more covered in horns and deformed than the usual Highbreed. The most disgusting part of him is his belly, which has what appears to be a cancerous mutation on it because he and his race can no longer breed thanks to generations of inbreeding. It disappears after Ben infuses him with Omnitrix DNA, apparently healing the deformity and causing him to turn red and appears more pleasing to the eyes.
* In "Save the Last Dance", Big Chill keeps possessing Ben and making him act ''very'' erratic. His eating habits and personality take a full 180-Ben acts much nicer toward Kevin and was shown eating through 2 pickle jars (juice and all)-and when Ben tries to transform into a different alien, Big Chill takes over anyway. When in Big Chill form, he becomes aggressive, devours anything metal (he ate an ''entire car wash''), growls and attacks people. The similarities to Zs'Skayr was ''very'' frightening even as it's revealed that Big Chill was doing that so it could ''reproduce''.
** Not only does Big Chill override an attempt to turn into another alien, there's a scene where Ben suddenly stops mid-sentence with a vacant stare before slowly activating the Omnitrix and transforming into Big Chil.
* "Time Heals" gives us an Alternate Future where Hex and Charmcaster killed Gwen and took over the world. While the scene of Bellwood being invaded with Charmcaster's golems is bad enough, we also get to see what they did to the two other heroes: Kevin was forced to absorb the substance the golems were made of, resulting in him becoming Charmcaster's personal slave. As for Ben, we get to find him in jail, in his Spidermonkey form.... suggesting they were [[AndIMustScream keeping him alive and forcing him to shapeshift just so they could torture him in his various forms]].
* "Above and Beyond" gives us a plot where the Plumber's Helpers are trapped on a space station with Ben, who has inexplicably turned AxeCrazy. While it eventually turns out to be [[SecretTestOfCharacter an act to test them]], this gives us an episode where Ben acts spectacularly creepy, stalking the Helpers throughout the station, attacking them out of nowhere, [[IShallTauntYou taunting]] [[BreakThemByTalking and lecturing them]] and generally acting like something between a slasher movie killer and an Evil Mastermind. Who knew Ben would make such a scary villain?
-->'''Manny:''' I know you're in here. Come out and show yourself! The others might be afraid, but I'm not scared of you!
-->'''Ben:''' That's because the others are ''smarter'' than you.
** The moments with Big Chill deserve a mention. Unlike in "Save the Last Dance", where Big Chill's actions were more feral, Big Chill in here acts just like Zs'Skayr from the Original Series episode "Ghostfreaked Out". It's also one of only two occasions where we see him smile.
*** Big Chill is completely surrounded by the Plumber's Helpers. He responds by hunching over, letting out a psychotic sounding EvilLaugh and then slowly sinks through the floor.
** Echo Echo subjecting Helen to a a circular Wall of Sound attack with her trapped in the center ([[CallingYourAttacks named as an]] [[PunnyName Echochamber]]) before all of his clones let out an EvilLaugh.
** Ben as Goop succesfully tricking Pierce into letting his guard down by [[SureLetsGoWithThat playing along with his assumption that something is controlling him]] before laughing and trying to ''suffocate him''.
--->'''Pierce:''' Ben, whatever's controlling you, you have to fight it!
--->'''Goop:''' Help me, Pierce. I can't stop myself! You're my only hope!
--->'''Pierce:''' What can I do to help?
--->'''Goop:''' "What can I do to help?" You're pathetic!
*** As Pierce flees, Goop turns back into Ben, who simply watches him run with a darkly amused expression.
---->'''Ben:''' You can run, but you can't hide.
** Ben [[StealthHiBye suddenly being right behind Alan]] as he turns around, in human form.
--->'''Ben:''' [[CreepyMonotone Where are the others, Alan?]]
** Grandpa Max's first message getting interrupted... by ''Humungosaur''.
*** Ben's later transformation into Humungosaur is presented as the Plumber's Helpers staring up in shock as his shadow slowly looms over them.
*** How do they ultimately defeat Humungosaur? They have to resort to launching him out of an airlock.
** Ben's default expressions in this episode? A KubrickStare and a PsychoticSmirk. It gets creepier when the dark lighting of the ship causes Ben's face to be illuminated by the glow of the Omnitrix's holograms.
[[/folder]]

[[folder: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 [[PoweredByAForsakenChild 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 AxeCrazy 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 [[WhatTheHellHero says he'd promised to try it her way]]:
-->'''Ben:''' Yeah. ''[[WhamLine I lied.]]''
* Zombozo shows up again, and while losing the source of his power has brought him down from "omnipotent god of MonsterClown-ness," he compensates by acting in a completely AxeCrazy, 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 ''[[EyeScream blinded]]'' [[EyeScream him]] in that encounter.
* [[https://www.youtube.com/watch?v=7MINhGzQhWc Inspector 13's really, really, really horrible]] EvilLaugh. 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 [[TheIgor 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 GoryDiscretionShot, 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 [[TakingYouWithMe 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 HeroicSacrifice 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 SaveTheVillain 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 AndIMustScream scenario is scary, but this one makes ''damn sure'' you're gonna be screaming. Forever.
* [[EldritchAbomination 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 FamilyUnfriendlyDeath 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?

[[/folder]]

[[folder: Omniverse]]
* In case Zombozo wasn't creepy enough in the original series and ''Ultimate Alien'', ''Omniverse'' gives him a more zombie-like appearance, with visible ribs, an apparently missing eye, and decayed flesh in some places.
** You should realize that this is his first appearance since Gwen punished him back in ''Ultimate Alien''? [[FridgeHorror Maybe this is the end result.]]
* Psyphon has become much more creepy and threatening, with a newer, more shark-like design, AxCrazy tendencies (he thinks about ''eviscerating'' one of his own henchmen), and actually managing to screw around with Ben's nerves.
** “Outbreak” puts it further with him. Two words : [[MagmaMan Pyronite Psyphon]].
** And in the mainly fun episode "Special Delivery", he charges himself up with a Dwarf Star and beats the crap out of ''Humungousaur''. Ben is suitably worried.
* The Nosedeenians in ''A Jolt from the Past'' screech in terror as Fistrick's men re-capture them and when Fistrick uses them to power his mech-suit. It's also implied that being forcibly drained of their electricity by Fistrick's tech is causing them extreme pain.
* Khyber's TrophyRoom is filled with bodies and body parts from various aliens that have been confirmed to be sentient over the course of the show. This includes a skull from a Vaxasaurian (Humungousaur's species), a helmet that looks like it belonged to the Sentient Ultimate Humungousaur from “The Ultimate Sacrifice” above in the Ultimate Alien section, The hook hand of [[WesternAnimation/TransformersAnimated Lockdown]], ''[[WesternAnimation/TransformersAnimated Grimlock]]'''s sword, a shell from a Geochelone Aerio (Terraspin's species), a Crabdozer head, and many others...
** Khyber himself has his moment. In “It Was Them”, when Ben is being trapped by one of his pet's forms, he is shown holding a long knife and saying "Soon", strongly hinting he was intending to ''behead'' Ben...
** Then in “Of Predators and Prey”, he outright states he plans to cut off Ben's hand and to keep it with the Omnitrix, even indicating where he plans to place it in his TrophyRoom. Even Ben seems disturbed.
* Malware's birth in Azmuth's flashback is very scary. When Azmuth disconnected the Helix, a yellow and black puddle leaked out, eventually shaping itself into a Galvanic Mechamorph. He then displays his ability to copy and destroy technology, seems weakened.... and rushes at the closest innocent Galvanic Mechamorph around with claws at the ready. [[GoryDiscretionShot And then the flashback cuts off]].
** Malware's appearance in “Of Predators And Prey” showcases that he's got a new, much more monstrous look to him, and it's shown that he, along with his associates, forced Phil, Max's old partner, to use the Nemetrix, with this experiment being shown, but [[NothingIsScarier scarcely seen]].
** “Malefactor” reveals the reason for Malware's monstrous appearance and all but demonstrates his KnightOfCerebus status. When he and Present Ben meet for the first time, Ben is furious and a bit scared at the sight of him. Now keep in mind that Ben himself stated that he's faced many foes such as [[TheDreaded Vilgax the Conqueror]] and [[EldritchAbomination Dagon the Destroyer]]. [[FridgeHorror What has Malware done to make Ben of all people scared of him?]] Malware even hinted at it, saying something to the effect of Ben knowing better than anyone what Malware is capable of. Chances are that he ''wasn't'' talking about the worst thing he'd done in that episode to that point (serving as a distraction so Khyber could scan this alien moth animal for the Nemetrix.)
** We also find out what his ArmCannon does. Malware assimilated a gun that takes an enemy apart on the cellular level and the effect can spread to anything with a similar genetic structure. If it were to hit a human, every human for 100 miles would basically turn to dust. It also means if Malware ''ever'' scores a direct hit on Ben or any other of our heroes, there's no OnlyAFleshWound, no "just stunned." No possible effect other than "you die, game over." Malware's no Zombozo, but every single time we see him, we ''add'' to the list reasons why you know if he's around, [[KnightOfCerebus shit just got real]].
** Malware endangering a busload of innocent children to escape from Ben is quite frightening. Especially ''right'' after the Sandy Hook massacre put endangering children right in the public's mind.
** And we finally find out ''why'' Ben's so afraid of Malware. He painfully tore Feedback (Ben's favorite alien from when he was 11) out of the Omnitrix and destroyed the form. As if that weren't bad enough, there's how he did it. Red lines spread over Feedback as either he or the Omnitrix emits a ''horrific'' [[HellIsThatNoise screeching noise that sounds like a dying fax machine mixed with AOL]], until Ben has been ''pulled out of him'' and Feedback is just hanging limply in Malware's hand before Malware ''causes him to wither and disintegrate into dust right in front of Ben!'' So on top of all the ''other'' reasons this guy is so scary, Ben knows he can destroy his aliens in a horrific fashion if he ever gets the chance. No wonder Ben's scared of him.
*** And it's also a traumatic experience for poor 11-year-old Ben. It filled him with such rage that he actually ''tried to kill Malware'' by setting the Omnitrix to overload the rogue Galvanic Mechamorph, [[NotQuiteDead Not only did Malware eventually reform himself and flee in secret]], the incident left Ben unable to turn into Feedback for the next five years. It also left him traumatized to the point where he won't even talk about Feedback in the present time.
** “Showdown, Part 1” also finally shows Malware killing two Galvanic Mechamorph guards onscreen, and the end of the same episode has Malware seemingly entering OmnicidalManiac territory by ''destroying Galvan B.''
** “Showdown, Part 2” shows Malware grow bigger than even ''Way Big'' and look even more horrific. This is even more punctuated by him ''absorbing Way Big into himself''.
** "Malgax Attacks" has Vilgax having Albedo fashion Malware's remains into a PoweredArmor. But what's scary is at the end. After Vilgax is defeated, ''[[SequelHook something black and red seeps out of Vilgax's petrified remains.]]''
*** On a related note: said PoweredArmor basically makes Vilgax look downright ''demonic''. And that's not counting the fact Vilgax spends the episode more or less ''wearing a corpse''.
* The Psycholeopterran whose DNA Khyber was taking is kinda hardcore. It makes you see your fondest desire, but it is a predatory beast. Most LotusEaterMachine scenarios give you a long time to realize the world's wrong and marshal your HeroicWillpower, or your friends come and rescue you, or something. This thing however... If you happen to encounter this thing in the wild, you've got about five seconds in la-la land before this thing ''eats you.'' And just think, ''aliens use this thing as a GRatedDrug.'' If it's improperly contained, enjoy your Website/{{Darwin Award|s}}.
* Billy Billions getting trapped in Dimension 12 is very frightening. Sure, [[LaserGuidedKarma he brought it on himself]] but think about it, he's trapped in a dimension where he cannot age and is hunted down by robots designed to destroy all organic life. That's scary.
** And it's also scary how ''close'' he came to getting rid of Ben. Ben was too busy with the thief he caught to notice someone gunning for him. Had he not been Diamondhead at the time, who's crystalline body deflected the laser, he would have been sucked into Dimension 12 and the Ben 10 universe would have been ''very'' different.
** For five years Billy's parents didn't know where he was. For five years, they had no idea their little boy was trapped in a dimension filled with killer robots. Truly, a parent's worst nightmare.
* “Store 23” was initially about Ben trying to find the legendary 23rd Mr. Smoothy store and lots of wacky hijinks ensue. Now, why is this episode on this page? Because Ben ''does'' find Store 23, and it turns out to be a unique Mr. Smoothy that travels between dimensions. The real shocker however comes when Ben stumbles into Dimension 23, whose native Ben Tennyson (dubbed Ben 23) is more of an AttentionWhore and has FantasticRacism against all aliens that aren't his Omnitrix transformations. The reason... in this dimension, Grandpa Max '''died''' ''before'' Ben obtained the Omnitrix. As a result, Ben 23 didn't get the moral support and CharacterDevelopment that would mold our Ben into the HumbleHero he is today. Wanna make it even worse? Ben 23 ''nearly [[MoralEventHorizon ripped his reality's version of Azmuth in half]]''!
* A weird variant, but Fistina's look with her Kraaho boyfriend in “Special Delivery” is [[UncannyValley kinda disturbing]]. Even the other villains are freaked out.
** That same episode gives us Toepick, one of the aliens mentioned in the Ben 10,000 future and hasn't been given a physical form until now. All that was said about this alien is that ''it grosses even Ben out''. At first it seems to be an ordinary alien with a helmet. [[PleaseKeepYourHatOn Then the faceplate opens, revealing a horribly grotesque face]]. [[TakeOurWordForIt We're never shown its face]], but if Psyphon's screams of terror are any indication, it's better if we didn't. Even more so, Zombozo is established as NightmareFuel incarnate, and yet Toepick terrified him at least as much as (maybe worse than) Ghostfreak.
* Toepick, as mentioned just earlier, hides his NightmareFace in a cage. According to WordOfGod, only Ma Vreedle, blind species, and robots aren't scared (though with robots it would trigger a defensive reaction).
** It heightens the nightmarish implications when both Psyphon with a Dwarf Star and Zombozo (you know, the closest thing the series has to a god of fear), are scared relentlessly by Toepick.
* Psychobos' MindControl serum when used on Revonnah. Seeing all those mind-controlled people acting so mechanical was somehow extremely creepy.
* “Frogs of War” has Psychobos and the Incurseans unleashing an army of mutated [[AttackOfThe50FootWhatever To'Kustar]] on Earth. While the most well known one is something of a CuteMonsterGirl, the others are more akin to ''berserk [[Anime/{{NeonGenesisEvangelion}} Evas]]'' with skeletal faces. [[https://vignette.wikia.nocookie.net/ben10/images/b/b2/Mutant_To%27kustar_official_artwork_%281%29.png/revision/latest?cb=20150802181902 Three]] [[https://vignette.wikia.nocookie.net/ben10/images/4/40/Mutant_To%27kustar_official_artwork_%282%29.png/revision/latest?cb=20150802181838 in]] [[https://vignette.wikia.nocookie.net/ben10/images/1/1a/Mutant_To%27kustar_official_artwork_%283%29.png/revision/latest?cb=20150802181811 particular]] are BodyHorror ''incarnate.''
* Rook and Max as zombie clowns. Zombie clowns in general, actually.
* Proctor Servantis, leader of the Rooters and serial [[MindRape mind rapist]]. His design is creepy enough, but then there's also his ''voice''. Charles Adler is usually known for playing funny characters, [[PlayingAgainstType but there is nothing funny about Servantis]], who is a [[TheStoic chillingly composed]] [[TheSociopath sociopathic]] KnightTemplar. He frequently snatched and experimented on various humans AND aliens alike (most notably, YOUNG ORPHANS), brainwashing them into becoming his loyal servants. The purpose? All to “stop” Ben Tennyson, as his inexperience with the powerful Omnitrix could be detrimental to the world, possibly the universe. Sounds kinda noble, right? Unfortunately, [[MurderIsTheBestSolution Servantis and the Rooters didn’t seem to care about leaving Ben alone with the device off his wrist, and insist that Ben must DIE along with it.]]
* In "Mystery, Incorporeal", Darkstar appears to have a cult under his control. He drains one of the girls in the cult of life force. Another girl, who appears to be her sister, replies by saying "Margie's so lucky" ''When Margie has just been left a dessicated husk. As if that is some kind of opportunity.''

[[/folder]]

[[folder: 2016 Reboot]]
* Ben screaming in pain as Vil drains the poor boy of his Gax form.
* Didn't think the Null Void could get any scarier? Now it's a completely monochrome dimension where time appears to be permanently frozen, where you are stuck drifting in silence and solitude forever. It's enough to make one miss all the monsters the original one had!
* The Antitrix's version of Gray Matter, Dark Matter: it looks less like a Galvan and more like a tall, lean (if not straight up malnourished) demon, able to contort his limbs in an innatural way. The fact it's a '''massive''' case of AdaptationalBadass doesn't help.
* Ben's nightmares in "Innervasion Part 2", caused by the High Override's influence. Especially the one where a bunch of Shock Rocks crawl out of a crater, one with Ben's face telling him he can't fight fate and one where he, as Shock Rock, crushes Gwen in his hand.
** Even worse is Ben getting in contact with the High Override at multiple times during the 5 Parter. Fred Tatasciore does a good job of voicing the Override; not to mention, the size of the Override! He’s about as tall as Way Big. Plus, he mind controls Ben into becoming one of his thousands of soldiers.
** While the event ends on a happy note, there’s still something left unaddressed; what happened with all the other Fulmini that got out of the watch?
* The Forever Knight. The Forever Knight is the cunning and manipulative antagonist of Season 3, usually hiding in the shadows while either Kevin or another villain does his dirty work. At this time, Ben has only fought him once, but the Forever Knight managed to play into Ben’s insecurities. It’s rather shocking coming from this show, seeing as it was playing it safe with the first two seasons.
** He only ends up getting worse as the season progressed, ultimately proving to be a full-fledged ''[[WesternAnimation/TeenTitans Slade]]'' {{Expy}}, with [[HarmfulToMinors all that this entails.]]
* The sounds of Kevin’s transformations. You can hear what appears to be screams and other wonderful horror noises.
* “Which Watch”: Charmcaster mutates Kevin into a horrible monster, and [[YouAreWhatYouHate her words echo]] [[DomesticAbuser a certain someone she was associated with...]]
* In “Safari So Bad”, Ben has his body taken over by a voodoo doll. Sounds like a Charmcaster or Hex plot, right? Wrong. His body is taken over by Tim Buktu, a grown man with no powers, who is obsessed with Ben after he managed to expose him for the fraud he was. The opening scene of the episode shows Tim obsessing over his defeat in a bathroom plastered with dozens of pictures of Ben’s aliens.
* Tetrax gets his arm torn off in Mutiny for the Bounty. He doesn't grow it back.
* Animo's BodyHorror in "Animorphosis" can be more than a little unsettling; bonus points for the part where Stink Fly's wings are being consumed by Heat Blast's fire, and the doctor is apparently screaming in pain.
* In "Welcome to Zombozo-Zone" Max (who has been hypnotized to believe he was a wild man) decides [[ImAHumanitarian to eat Gwen]].
** Later, when they are both free from the hypnosis, they are captured by a mind controlled Ben, who decides to feed them a group of feral badgers. At least one almost bites off Gwen's face.
* It is made clear that the Alien X featured in ''Alien X-Tinction'' ''killed'' at least a few Ben Tennysons, and possibly their Gwens and Maxes. The Ben in the cold opening was at least able to live, but the Ben from Maximillian's universe was not so lucky. Keep in mind that all of these Bens were minors as young as 10.
** When Alien X is revealed to be an alternate version of Ben who is cynical, believing he could do everything on his own. His origin tells that while fighting his universe's Vilgax, Grandpa and Gwen tried to help him. Which resulted in Vilgax killing them with his Laser eyes, we can see Ben watched in horror and this apparently has pushed him into who he was today.

** Khyber himself has his moment. In “It Was Them”, when Ben is being trapped by one of his pet's forms, he is shown holding [[KnifeNut a long knife]] and saying "Soon", strongly hinting he was intending to ''behead'' Ben...

** 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 (probably due to the fact their debuts were later), but if they DID, Ben would have been dead in a few seconds.

** What's worse is how he was beaten. Ghostfreak. All we see is Ghostfreak's back to the camera as he pulls apart his body to reveal a mass of tentacles to Zombozo. It was only a taste of what was to come. (Not to mention... ''Ben'' has a form that a HumanoidAbomination is ''afraid'' of?!)

* “Which Watch”: Charmcaster mutates Kevin into a horrible monster, and [[YouAreWhatYouHate her words echo]] [[BastardBoyfriend a certain someone she was associated with...]]

** And to throw in some AdultFear, for five years Billy's parents didn't know where he was. For five years, they had no idea their little boy was trapped in a dimension filled with killer robots. Truly, a parent's worst nightmare.

[[quoteright:268:https://static.tvtropes.org/pmwiki/pub/images/gwen_is_frozen.png]]
[[caption-width-right:268:DarkerAndEdgier indeed...]]

** 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 EvilLaugh [[https://www.youtube.com/watch?v=7MINhGzQhWc]]. Even Ben is creeped out.

-->'''Pierce:''' Ben, whatever's controlling you, you have to fight it!
-->'''Goop:''' Help me, Pierce. I can't stop myself! You're my only hope!
-->'''Pierce:''' What can I do to help?
-->'''Goop:''' "What can I do to help?" You're pathetic!

-->'''Ben:''' You can run, but you can't hide.

-->'''Ben:''' [[CreepyMonotone Where are the others, Alan?]]

* The Highbreeds could be creepy on occasions, especially the one who was about to punish Simian at the end of his debut episode. Ben tricked Simian into carrying a DNAlien ear cleaner, which unlike human ears, need ''acid'' to flush out... and the Highbreed now has it in his possession:

* The Highbreeds could be creepy on occasions, especially the one who was about to punish Simian at the end of his debut episode. Ben tricked Simian into carrying a DNA alien ear cleaner, which unlike human ears, need ''acid'' to flush out... and the Highbreed now has it in his possession:

* Highbreed Supreme is especially disturbing to look at- initially. Pale, [[FatBastard fat]], and with a face even more covered in horns and deformed than the usual Highbreed. The most disgusting part of him is his belly, which has what appears to be a cancerous mutation on it because he and his race can no longer breed. It disappears after Ben infuses him with Omnitrix DNA, apparently healing the deformity and causing him to turn red and appears more pleasing to the eyes.

* [[EldritchAbomination Dagon]]; his minions, the Lubracas, 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 FamilyUnfriendlyDeath to Sir George, by striking him with lightning, stripping him of his immortality and turning him to ashes.

* * In Mystery, Incorporeal, Darkstar appears to have a cult under his control. He drains one of the girls in the cult of life force. Another girl, who appears to be her sister, replies by saying "Margie's so lucky" ''When Margie has just been left a dessicated husk. As if that is some kind of opportunity.''

* It's kind of a scary world to live in because of how easily it seems the world is doomed. One Xenocyte? Your whole world contains nothing but [[FacelessMooks DNAliens]] in short order. Death Star class ray guns are available to even ''comedic'' villains. Many planet, including [[InsignificantLittleBluePlanet Earth]], are considered so insignificant that the [[SpacePolice Plumbers]] will sometimes not even bother ensuring security to protect them, meaning few people would lay a finger if someone suddenly decides to conquer or destroy Earth (even in the light-hearted iteration ''Omniverse'', a character threatens to destroy Earth [[DisproportionateRetribution because a guy living on it won't marry his daughter]], and encounters ''no resistance whatsoever'').

* “Everybody Talks About The Weather”: let's talk about what happens to the victims frozen by [=DNAlien=] Freeze Guns. They are frozen in a bluish-grey metal substance that can remain solid at normal temperature yet keep its victims in hibernation at a sub-zero temperature. It happens so quickly too with the victims barely having any time to react with only a scream of agony as they're hit before they're quickly and completely encased in metal. Basically, they are instantly frozen, in a substance that ''will not'' melt under normal circumstances, essentially turning them into living metal statues. Meaning, that the heroes could've remained frozen ''forever'' and [[TheBadGuysWin the villains would have won]] if not for both Swampfire (And Ben ''being'' Swampfire at the time) and Alan's extreme heat abilities allowing them to thaw everyone out. Just seeing people frozen this way can be very unnerving, to say the least. To make matter worse it's implied the victims [[AndIMustScream are still conscious!]]

* “Everybody Talks About The Weather”: let's talk about what happens to the victims frozen by [=DNAlien=] Freeze Guns. They are frozen in a bluish-grey metal substance that can remain solid at normal temperature yet keep its victims in hibernation at a sub-zero temperature. It happens so quickly too with the victims barely having any time to react with only a scream of agony before they're completely encased in metal. Basically, they are instantly frozen, in a substance that ''will not'' melt under normal circumstances, essentially turning them into living metal statues. Meaning, that the heroes could've remained frozen ''forever'' and [[TheBadGuysWin the villains would have won]] if not for both Swampfire (And Ben ''being'' Swampfire at the time) and Alan's extreme heat abilities allowing them to thaw everyone out. Just seeing people frozen this way can be very unnerving, to say the least. To make matter worse it's implied the victims [[AndIMustScream are still conscious!]]

* “Everybody Talks About The Weather”: let's talk about what happens to the victims frozen by [=DNAlien=] Freeze Guns. They are frozen in a bluish-grey metal substance that can remain solid at normal temperature yet keep its victims in hibernation at a sub-zero temperature. It happens so quickly too with the victims barely having any time with only a scream of agony to react before they're completely encased in metal. Basically, they are instantly frozen, in a substance that ''will not'' melt under normal circumstances, essentially turning them into living metal statues. Meaning, that the heroes could've remained frozen ''forever'' and [[TheBadGuysWin the villains would have won]] if not for both Swampfire (And Ben ''being'' Swampfire at the time) and Alan's extreme heat abilities allowing them to thaw everyone out. Just seeing people frozen this way can be very unnerving, to say the least.

* “Everybody Talks About The Weather”: let's talk about what happens to the victims frozen by [=DNAlien=] Freeze Guns. They are frozen in a grey metal substance that can remain solid at normal temperature yet keep its victims in hibernation at a sub-zero temperature. Basically, they are instantly frozen, in a substance that ''will not'' melt under normal circumstances, essentially turning them into living metal statues. Meaning, that the heroes could've remained frozen ''forever'' and [[TheBadGuysWin the villains would have won]] if not for both Swampfire (And Ben ''being'' Swampfire at the time) and Alan's extreme heat abilities allowing them to thaw everyone out. Just seeing people frozen this way can be very unnerving, to say the least.

* “Everybody Talks About The Weather”: let's talk about what happens to the victims frozen by [=DNAlien=] Freeze Guns. They are frozen in a grey metal that can remain solid at normal temperature yet keep its victims in hibernation at a sub-zero temperature. Basically, they are instantly frozen, in a substance that ''will not'' melt under normal circumstances, essentially turning them into living metal statues. Meaning, that the heroes could've remained frozen ''forever'' if not for both Swampfire (And Ben ''being'' Swampfire at the time) and Alan's extreme heat abilities allowing them to thaw everyone out. Just seeing people frozen this way can be very unnerving, to say the least.

** Just look at the picture of Gwen, after being frozen by one of the Freeze Guns, for example. The way her eyes are open wide in fear, her mouth frozen in an eternal scream of agony, the way her hands are trying to reach out futilely for help... She could've been frozen like that ''forever''...