History NightmareFuel / Ben10

** Even worse, there is a apparently a galactic code of conduct established by the Galvans to prevent massive loss of live that allows an individual to ''legally'' conquer a planet with no outside resistance whatsoever or interference from the Plumbers as long as they defeat the strongest fighter from the planet they are conquering. This allowed Vilgax of all people to conquer ten planets including Ultimos's home planet and would have controlled Earth with no resistance if he managed to defeat Ben.

* Most series in the franchise make it a tradition of showing detailed transformation sequences where we see Ben shapeshifting into his alien forms. Many of them tend to involve quite a lot of BodyHorror:

** Fourarms, [=XLR8=] and Wildmutt in the original series have Ben's muscle growing in a quite disturbing way, making it look like his nerves are becoming apparent.

* Eon in his first (albeit non-canon) appearance was damned ''creepy.'' What do you do when a TimeMaster doesn't like you? [[Series/DoctorWho Basically, run]]. His time ray causes RapidAging, and the first guy we saw him used it on looked like a half-decomposed corpse... and was still alive. His body had become so brittle that at one point, a not-very-hard touch causes the guy's arm to break off (and we learned his ability to feel pain was very much intact.) You probably sighed with relief when the poor guy [[AlmostDeadGuy finished his exposition]] and died. There's also the way he stalked Ben: staying out of step with reality, he could follow Ben anywhere unseen. You know that weird little blur in your class picture? That's him. Watching you. It's hard to describe, but the handling of him when he'd approach Ben was more like a horror movie's supernatural foe than one of Ben's standard enemies. Also, when he's around, ''no one'' can help Ben, because Eon is fond of TimeStandsStill. You and a bunch of heavily armed Plumbers are getting ready to show this guy who's boss... and suddenly Robert Picardo starts to talk... very... slowly. Then you're the only one moving... you, and the guy responsible for the most FamilyUnfriendlyDeath in franchise history, who hasn't done it to you ''yet'' because he ''needs'' you, and who's been looking over your shoulder at school and at home and ''everywhere.'' Unlike Vilgax or Diagon or any other BigBad, there's not an alien in Ben's arsenal[[note]]Okay, he'll eventually get Clockwork.[[/note]] that makes Eon less of a threat. Every time Ben encountered him - and all the times Ben had no idea he was there - Eon could have killed Ben at his leisure and there'd have been nothing Ben could do. His plan needed Ben alive and that's why Ben is still here.
** When he returns in ''Ultimate Alien'' he's using his power to its maximum level, outright turning to dust anything he hits with it. He also gets a reputation as HeroKiller - he's ''hunting'' Bens one parallel dimension at a time, and ours is just next on the list. ([[spoiler:It turns out they're not dead, though: his {{Mooks}} are the alternate Bens, brainwashed.]]) Ben gets lucky in that his alien forms leave his human form behind unharmed if they get dusted, though he loses the ability to transform into that alien. (They're restored, though.) He's no longer getting the horror movie treatment, but you still hold your breath with him.
* 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 treatens to destroy Earth [[DisproportionateRetribution because a guy living on it won't marry his daughter]], and encounters ''no resistance whatsoever'').

** Ghostfreak has Ben's head turning into a skull during the first part of the transformation. It’s even worst in ''Alien Force'', where we get to see his spin distorting, his claws emerging in a Wolverine-like way from his hands, and his skull making a 180° turn;

* 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 show WesternAnimation/Ben10Omniverse, a character treatens to destroy Earth [[DisproportionateRetribution because a guy living on it won't marry his daughter]], and encounters ''no resistance whatsoever'').

*** We commonly hear of Ben's exploits on the news and such; "those alien heroes" are well known before Ben's secret identity is exposed in Ultimate Alien. It's not like the world's unaware of all this stuff, even though this incident doesn't get directly mentioned. Of course, with Yellowstone turned into a DeathWorld, it's entirely possible people saw but just didn't survive to report.

* ''Everybody Talks About The Weather'': 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, the victims are frozen in a substance which will not melt under normal circumstances. Meaning, that the heroes could've remained frozen ''forever'' if not for Swampfire's abilities. Seeing people frozen in this way can be very unnerving.
** Look at [[https://static.tvtropes.org/pmwiki/pub/images/gwen_is_frozen.png Gwen]] for example. The way her eyes are shut tight 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''...

* The episode introducing Darkstar was downright creepy; the episode starts with a scene of a schoolgirl running at a house and desperately calling for help. The door open, we get something that looks like a GoryDiscretionShot, and cut to the girl walking around in the street, now zombified.

* ''The Gauntlet'' has Cash, oridinary 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 him, causing him to become completely psycho and attempt to [[DisproportionateRetribution kill Ben as a revenge for making him look ridiculous in front of his class]]. And 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 it not be stopped, he would have probably been permanantly mutated into a Techadon.

** 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 Inkursians shows us Emperor Milleus disintegrating his own lieutnant ''on-screen'' because [[YouHaveFailedMe he failed to find and bring back his daughter.]]

* Reirassic 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. Kinda cool-looking, but also scary.

* In ''Save the Last Dance'', Big Chill keeps possessing Ben and making him act ''very erratic''. When Ben tried to turn into another alien, he transformed into Big Chill, his eating habits and personality go 180--Ben acts much nicer toward Kevin and was shown eating through 2 pickle jars (juice and all) and Big Chill took over Ben to transform. When in Big Chill form, he becomes aggressive, devour metal, growls and attack people. The similarities to Ghostfreak was ''very'' frightening [[spoiler: even as it's revealed that Big Chill was doing that so it could ''reproduce.'']]
* ''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 absob the substance the golem were made of, resulting in him becoming Charmcaster's personnal slave. As for Ben, we get to find him in jail, in his Spider-Monkey 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 an plot where the Plumber's Helpers are trapt on a space station with Ben, who has inexplicably turned AxeCrazy. While [[spoiler:it eventually turns out to be an act to test them]], this gives us an episode where Ben acts spectacularly creepy, stalking the Helpers through 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?

* 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 all 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 worst, his final plan was to [[spoiler:[[PoweredByAForsakenChild absorb a Celestiansapien child]]]]. This guy was in many way similar to Kevin 11 in the Ben 10,000 future where he didn't reform.

* 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, 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!"

* In case Zombozo wasn't creepy enough in the original show and ''Ultimate Alien'', ''Omniverse'' gives him a more zombie-like appearance, with visible ribs, an apparently missing eye and decayed flesh in some places.
** Realize that this is his first appearance since Gwen punished him in ''Ultimate Alien''? [[FridgeHorror Maybe this is the end result.]]

** ''Outbreak'' puts it further with him. Two words : [[MagmaMan Pyronite Psyphon]].

** 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...
** Then In ''Of Predator and Preys'', 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; when Azmuth disconnect the Helix, a yellow and black Galvanic Mechamorph matter emerge from it, shaping itself into him. He then displays his ability to copy tech, seems weakened.... and rush his claws at the closest innocent Galvanic Mechamorph around. [[GoryDiscretionShot And then the flashback cuts off]].
** Malware's appearance in ''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, [[spoiler: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 Diagon 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, 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]].

** ''Showdown'' also finally shows Malware killing two Galvanic Mechamorph guards onscreen, [[spoiler: and the end of the same episode has Malware seemingly entering OmnicidalManiac territory by ''destroying Galvan B.'']]
** ''Showdown Part 2'' shows Malware [[spoiler:grow bigger than even ''Way Big'' and look even more horrific. This is even more punctuated by him ''absorbing Way Big into himself'']].

* Billy Billions getting trapped in Dimension 12 is guite 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 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.
* ''Store 23'' was 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? [[spoiler: Because Ben stumbles into a universe where 23 Ben is more of an AttentionWhore and has FantasticRacism against all aliens since Max died ''before'' Ben got his Omnitrix. As a result, 23 Ben didn't get the moral support and CharacterDevelopment that would make him become the hero he was today. Wanna make it even worse? He ''nearly [[MoralEventHorizon ripped this dimension's 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 Ben's aliens. At first it seems to be an ordinary alien with a helmet. [[PleaseKeepYourHatOn Then the faceplate opens, revealing it's 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 (maybe worse) than Ghostfreak.

* ''Frogs of War'' has Psychobos and the Inkursians unleashing an army of genetically engeenered [[AttackOfThe50FootWhatever To'Kustar]] on Earth. Nuff says.

** Heatblast has Ben's skin being gradually covered with rock then being set on fire;
** Ripjaw show's Ben's mouth distorting itself and growing monstrous teeth;
** Fourarms, [=XLR8=] and Wildmutt in the original series have Ben's muscle growing in a quite disturbing way, making it look like his nerves are becoming apparent;

** Ghostfreak has Ben's head turning into a skull during the first part of the transformation; it's even worst in Alien Force, where we get to see his spin distorting, his claws emerging in a Wolverine-like way from his hands, and his skull making a 180° turn;

* Eon in his first appearance was damned ''creepy.'' What do you do when a TimeMaster doesn't like you? [[Series/DoctorWho Basically, run]]. His time ray causes RapidAging, and the first guy we saw him used it on looked like a half-decomposed corpse... and was still alive. His body had become so brittle that at one point, a not-very-hard touch causes the guy's arm to break off (and we learned his ability to feel pain was very much intact.) You probably sighed with relief when the poor guy [[AlmostDeadGuy finished his exposition]] and died. There's also the way he stalked Ben: staying out of step with reality, he could follow Ben anywhere unseen. You know that weird little blur in your class picture? That's him. Watching you. It's hard to describe, but the handling of him when he'd approach Ben was more like a horror movie's supernatural foe than one of Ben's standard enemies. Also, when he's around, ''no one'' can help Ben, because Eon is fond of TimeStandsStill. You and a bunch of heavily armed Plumbers are getting ready to show this guy who's boss... and suddenly Robert Picardo starts to talk... very... slowly. Then you're the only one moving... you, and the guy responsible for the most FamilyUnfriendlyDeath in franchise history, who hasn't done it to you ''yet'' because he ''needs'' you, and who's been looking over your shoulder at school and at home and ''everywhere.'' Unlike Vilgax or Diagon or any other BigBad, there's not an alien in Ben's arsenal[[note]]Okay, he'll eventually get Clockwork.[[/note]] that makes Eon less of a threat. Every time Ben encountered him - and all the times Ben had no idea he was there - Eon could have killed Ben at his leisure and there'd have been nothing Ben could do. His plan needed Ben alive and that's why Ben is still here.

* A weird variant, but Fistina's look with her Krahoo boyfriend in ''Special Delivery'' is [[UncannyValley kinda disturbing]]. Even the other villains are freaked out.

* Toepick, with his NightmareFace can supposedly scare almost anyone according to WordOfGod. Only Ma Vreedle, blind species, and robots are immune. Granted, we never see the face itself, though the implications are truly horrifying.

** And in the mainly fun episode "Special Delivery", he charges himself up with a Dwarf Star and beats the crap out of ''Humongosaur''. Ben is suitably worried.

** Khyber himself has his moment. In ''It Was Them'', when Ben is being trapt 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...

* Malware's birth in Azmuth's flashback; when Azmuth disconnect the Helix, a yellow and black Galvanic Mecamorph matter emerge from it, shaping itself into him. He then displays his ability to copy tech, seems weakened.... and rush his claws at the closest innocent Galvanic Mecamorph around. [[GoryDiscretionShot And then the flashback cuts off]].

* Khyber's TrophyRoom is filled with bodies and bodyparts from various aliens that have been confirmed to be sentient over the course of the show. This includes an Ultimate Humongousaur skull, ''[[WesternAnimation/TransformersAnimated Grimlock]]'''s sword, a Terraspin shell and many others...

** ''Malefactor'' reveals the reason for Malware's monstorous appearance and all but demostrates 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 Diagon 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, 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.)

* The Psycholeopteren 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, 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}}.

* 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 all his story arc, usually using the protagonists as pawn. And he was ready to absorb (which might as well be kill) five aliens in order to get their powers. Even worst, his final plan was to [[spoiler:[[PoweredByAForsakenChild absorb a Celestiansapien child]]]]. This guy was in many way similar to Kevin 11 in the Ben 10,000 future where he didn't reform.

* 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 Dnaliens you've seen up until now, only as monkeys with four arms. Surreal and scary, huh?

** The place where he's fought in the end makes it worse. Basically, it's like being inside a DisneyAcidSequence, only significantly less cute. The guy is ''supremely'' creepy, especially because this is usually a sci-fi show. This guy isn't an alien, or someone who got this hands on phasers. He's a HumanoidAbomination who ''steals happiness'' and creates a bizarre netherworld with AlienGeometries at his command. Everything about him takes the subverted cuteness that makes a MonsterClown up to a cosmic, reality-bending scale, and we never find the man behind the curtain, never get the "ah, here's his Holodeck-maker" or "'stealing happiness' means his AppliedPhlebotinum does this or that to your brain chemistry" DoingInTheWizard moment... and it also doesn't work like any magic we see with Hex and Charmcaster (and Gwen, once she steals Charmcaster's book). He doesn't play by the rules we know, he and everything about him simply '''is.''' He will feed on your very soul. He will turn your reality outside in. How? He just '''does,''' it's just what he ''is.'' If HP Lovecraft had created TheJoker, you would have this guy.

** This was retconned as the Hightbreed merely imprisoning him ''Ultimate Alien'', but still creepy...

* [[EnfantTerrible Kevin 11]]; the character initially appears as being a mere punk with powers... until we find out he is ready to kill thousands of people just to get money. The SlasherSmile he displays in some scene also contribute.

** 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. ''Omniverse'' hints that he might still be out there. (Of course, as a LighterAndSofter series, he'll probably be more like his first appearance than his second if he does. Then again, ''Omniverse did'' give us [[VileVillainSaccharineShow Malware]].)

** The whole idea of the 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 24/7 indefinitely." Ben and company had to call a Galvan doctor to SaveTheVillain because there's no way to remove it without your face 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.

** It's then revealed multiple girls suffered the same fate. As the protagonists try to figure out what happened with the help of who seems to be the local superhero. Eventually turns out said hero, despite possessing light powers, ''is'' the responsible: he charges his powers by feeding over energy from schoolgirls he seduces, eventually turning them into zombies slaves that he relies on to feed him even more. His habit to drain energy from them is played subtly like rape. To make matters worst, he succeeds in draining ''Gwen''.

*** 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.

* In the episode "Last Laugh", [[FishPeople Ripjaws]] deals with a robber by ''pulling him underwater''. The robber isn't seen again.

** Look at [[http://static.tvtropes.org/pmwiki/pub/images/gwen_is_frozen.png Gwen]] for example. The way her eyes are shut tight 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 ''forever''...

[[caption-width-right:268:Sweet dreams, kids...]]

[[quoteright:268:http://static.tvtropes.org/pmwiki/pub/images/Zombozo_scary_5637.PNG]]

* ''Everybody Talks About The Weather'': 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, the victims are frozen in a substance which will not melt under normal circumstances. Meaning, that the heroes could've remained frozen ''forever'' if not for Swampfire's abilities. Seeing people frozen in this way can be very unnerving.

** And then Ghostfreak succeeds in what he had been trying all along: possessing Ben.

** There's also those water-absoring tentacles that pop out of his chest when he opens a few skin flaps on it- yecchh!!

-->'''Manny''':I know you're in here. Come out and show yourself! The others might be afraid, but I'm not scared of you!

* Damn near the entirety of the episode "Camp Fear". The title alone should have clued you in.

*** It's even harder to watch his first transformation into Heatblast, considering the fact he looked completely terrified and, the more worrying part is, for all we know it could've also been an ''immensely'' painful experience for him. Physically.