As a Nightmare Fuel page, all spoilers are unmarked as per wiki policy. You Have Been Warned!
"We'll be BACK!"
While The Adventures of Jimmy Neutron, Boy Genius has developed a cult following for its unique animation style and interesting storytelling, those same elements can add some horror to the mix if DNA Productions wanted to.
- In the episode "The Trouble with Clones" Evil Jimmy tricks Jimmy into thinking he'd been turned good, and creates chaos in Retroville to distract Jimmy from his real plan, to create a duplicate Earth that's sapping reality from the original, not helping matters is the fact that Clone Earth is every bit as evil as Evil Jimmy is. Jimmy proceeds to reverse the process, presumably killing every one of the billions of evil humans.
- Many of the evil duplicates of Jimmy's friends, family, and acquaintances are shown to be highly disturbing. Evil Jimmy's parents are shown to be the most deranged as Evil Judy is shown gleefully dirtying her house while Evil Hugh laughs sadistically after recounting how he killed and mounted ducks on his wall as they begged for mercy.
- "One of Us" can get surprisingly scary at times, especially when Jimmy finds himself alone with his rival/potential love interest Cindy Vortex among a city that's been brainwashed and turned into perpetually happy zombies. The ending's rather intimidating as well: as the grandmother behind the mass mind control, Grandma Taters, boards the mothership, it seems like the episode will only end on a peculiar "WTF" note. Instead, Taters turns around, lifts her glasses to reveal completely black eyes, and says "WE'LL BE BACK." in a terrifyingly deep voice. And to make matters worse, Grandma Taters returned in the series finale, where she very casually reveals she eats humans, putting her original plan into a much darker light.
- The Nanobots trying to delete everyone from existence due to them being "flawed", thinking they're doing their job of fixing errors correctly. They came very close to succeeding as well, leaving Earth a Ghost Planet with the only two humans left being Jimmy (who they were saving for last) and Hugh (who they didn't notice). If Jimmy had taken even a moment longer to defeat the Nanobots, they would have cleared the data from their full Recycle Bin, which would have rendered everyone impossible to restore.
- "Sheen's Brain" where Sheen's head eventually gets so big it takes over his body and he develops psychic powers. And then his voice turns demonic when he starts speaking. Worse, his IQ would keep on growing infinitely until his head explodes. Sheen also becomes a sociopath and Knight of Cerebus — to the point where he declares himself a God and nearly kills "Ultra Lord" (actually a disguised Jimmy and Carl), his lifelong idol, for trying to revert him to normal.
- While "The N-Men" is an awesome homage to the superhero genre, it's when Jimmy hulks out that the story takes a surprisingly shocking turn. He did have a superpower. He just didn't tap into its potential. Enraged at all the mockery he got, and the fact that his work on a cure has been undone, he completely snaps. You get a close-up of his eye, and they turn from Innocent Blue Eyes into a bloodshot bright green and his voice drops in octaves. The camera quickly pans as Jimmy's body changes off-screen (but you can see his shadow growing larger and more muscular). You can hear his bones crunching and Jimmy sounds like he's under excruciating pain. And poor Goddard is Forced to Watch the whole thing in absolute horror.Jimmy: [growling] What's wrong with me? [voice deepens as his eyes change color] Feeling strange... [Goddard cowers in fear as he watches Jimmy transform] Thoughts cloudy, image of Cindy BURNING IN MY BRAIN!!! [smashes the door and goes outside in his new Hulk form] Jimmy did get superpower! Now Jimmy strong! [looking at the camera] Now Jimmy SMASH!! [roars as he runs towards the camera]
- "Win, Lose, or Kaboom":
- The basic rules of the game show Intergalactic Showdown are that all losing teams have their planets blown up! Worse is host Meldar Prime takes sadistic pleasure in demolishing the losers' planets even more than hosting the game itself. How many innocent planets has Meldar's show destroyed?!
- During the race between Jimmy's team and the team of brainy aliens. When it seems like they have made it to the finish line, they return to Retroville and find it completely empty. Then they hear ghostly voices that are haunted and strange in the Candy Bar. Inside the Candy Bar, they are suddenly greeted by their parents (all giving a rather weird smiles with their eyes creepily distorted) with a celebration of their supposed victory. When they find some things off (like the ice cream tasting like sheet rock), the "parents" urged them to "Eat and Forget" repeatedly in an increasingly unsettling manner like zombies. It was all a dream implemented by the brainy aliens to distract them; the only way they could wake up is to fall into the void outside where they find out they are in the middle of nowhere. It could be worse, think about what would have happened if the "parents" had captured the kids.
- Flippy. Hugh purchases a puppet named Flippy to practice ventriloquism, but his comedy routine is lacking, so Jimmy puts a computer chip in Flippy's head to enhance Hugh's brain. Instead, Flippy uses the chip to draw consciousness from Hugh to give himself sentience and become a real person who happens to be malevolent and pretty sociopathic, while Hugh loses his mind and becomes a lifeless empty shell. When Jimmy caught on, Flippy threatened to destroy Hugh's brain, since he controlled Hugh's body. When he gained full sapience, Flippy planned to kill Hugh by chucking his body off a cliff so Hugh couldn't get his brain back. Worse off, even though Jimmy manages to destroy the chip, it's implied in the end Flippy is still alive and still has some control over Hugh's mind.
- In "Who's Your Mommy", Carl gets impregnated by a single alien egg Alien facehugger-style. Jimmy is terrified by the situation and describes how the alien is a glowing mass of energy that could kill Carl via electrocuting him, growing till it splits him in half, or eating his insides once it's born, but everyone else including Carl's parents react with utter joy at Carl's pregnancy. Then the alien behind the facehugger that laid the egg, which happens to look like a giant lightning spewing jellyfish, comes all the way to Earth to look for its baby!
- "Sleepless in Retroville", where Jimmy, Sheen and Carl have a sleepover with a machine that cranks out scary stories, pillows, and pizzas. The climax is when Carl accidentally creates a flesh-eating pizza monster that chases them around the house, and is able to split into three pizza slices, as well as a pack of pillow monsters that go after Jimmy's parents. At the end after disaster seems to be averted, the pizza monster strikes back - "Haven't you ever heard of sequels?" Then it spirals into a series of nightmares from each of the characters. While most of them are funny, one ends when Carl tries to hide under Hugh and Judy's bed, but gets stuck and is eaten by the pizza slices. Yikes.
- "The Evil Beneath" has Dr. Sidney Moist, one of Jimmy's scientist role models and leading researcher in phyto-chemicals compounds who was thought long dead. He ends up revealing that he's been kidnapping people who come to the Quadrangle to turn them into Algae-based manservants because of his own psychotic paranoia that newcomers were sent to spy on him. He's done this many times and would have successfully done it to Jimmy and his friends if not for Jimmy finding a way to overload the Algae Men and destroy Dr. Moist's lab. Afterward, a dense fog appears out of nowhere with multiple pairs glowing red eyes inside the fog, and Jimmy and company flee in terror.
- "Nightmare in Retroville": Jimmy's monster machine that he created in an attempt to make his friends look like monsters for Halloween actually turned them into real monsters, by mutating their molecular structure on a subatomic level and altering their DNA. As such, Carl becomes a real vampire, Sheen becomes a real werewolf, and Hugh becomes Frankenstein's Monster. And in their monster states, Carl and Sheen become hell bent on killing or turning others into monsters themselves, with Carl turning Cindy into a bloodsucking vampiress and Sheen stalking Libby before turning her into a hungry she-wolf.
- At one moment in "Monster Hunt", something both cryptic and very unsettling is revealed:Betty: Gadgets go in the water! You go in with the gadgets! Monster in the water. Our monster.
Jimmy: Wait. Who goes in the water?
Betty: YOU do!
Carl: Why does the monster go in with the gadgets?
Sheen: No no, the monster goes in with the water.
Carl: Our monster?- For anyone who's still confused... Betty intends on using Jimmy as bait to lure out the Lake Monster? A crazy old man was willing to kill a child to catch something that for all anyone could know doesn't even exist.
- Captain Betty's backstory is pretty creepy too, despite the Bathos surrounding it. He was harvesting sea monkeys (here depicted as actual monkeys) for a mail order company when suddenly his ship was attacked by the monster. Not only did the monster eat his hand, as shown earlier, but it also devoured every last one of the sea monkeys he caught. The ominous way he tells the story, right down to describing the sea monkeys' screams, implies that the incident traumatized him (possibly explaining why he's so loony now) and it haunts him even to this day. And THAT'S why they call him Betty!
- Jimmy's entire situation in "The Eggpire Strikes Back". Picture yourself in his shoes: you saved your town from an evil alien race some months ago, and they come back for, at first, unknown purposes. Instead of taking over right away, they claim to come in peace and bring everyone gifts, emotionally manipulating the town with their own interests and desires. Despite your efforts to prove their true intentions, the town that you protected starts doubting you as the alien race in question takes it over. By the time you finally figure out what it is they're planning (reviving their dead chicken god to feast on the town), you've become a social pariah to everyone, including your best friends, and even your parents are embarrassed of your supposed prejudice. Then the truth comes from the alien leader's mouth: they all want to get revenge on you, the boy that put a stop to their plans the first time. They plan to leave you begging and pleading for everyone to believe you about their imminent doom, only to watch helplessly as the people you know and love are devoured one by one, all while your enemies simply laugh at your failure, all caused because of your heroic actions. That's what Jimmy has to go through; if it wasn't for Cindy realizing she helped the Yolkians with their evil intentions, this episode would have ended quite a bit differently...
- Cindy being strangled by a boa in "Stranded" is Played for Laughs but her pale blue face, bulging eyes and overall painful expression make it look like she really is about to die.
- Paul the chimpanzee from the DNA Productions logo at the end of every episode can be unnerving to some viewers because of his third eye.
- The Twonkies. Indestructible, vicious, and downright ravenous little Gremlin-like creatures that are drawn to destroy sources of good music, that start off looking like adorable little puffy creatures before coughing, gaining black eyes, and sprouting claws. Worse off, if you put too many of them in one place, they'll merge to become a massive indestructible Twonkie.
- One scene has a cute little squirrel minding its own business before coming face-to-face with a pack of Twonkies, who proceed to surround it like predators and presumably maul it offscreen. It's the only time in the special where the monsters are implied to have killed another living creature.
- Jimmy invents a candy that's so delicious, it becomes addictive. It gets so bad that everyone becomes like drug addicts and even try to kill Jimmy when he dumps all the candy and tells every one that there's no more. Even his parents become addicted! It takes the electric candy to make them stop.
- The episode where the gang goes to Retroland to try to disprove a ghost myth, with different people showing up dressed as the ghost to try to scare them. For the most part, it's funny, but than, at the end, the real ghost appears to Jimmy's parents, and the episode just ends there. Thankfully, later episodes indicate they somehow managed to escape.
- Though there's a bit of Mood Whiplash when the phantom showed up just to help Hugh with his list of pie flavors.
- While "Grumpy Young Men" is a mostly funny episode, the sheer fact that Jimmy, Carl, and Sheen are close to dying via Rapid Aging can be unnerving. Jimmy outright says the three of them would continue to age until they were Reduced to Dust at 6:03 P.M.… they just barely get back to normal with seconds to spare.
- The renegade Mc Spankeys in "Men At Work". After Hugh causes the restaurant's AI to go haywire, it then comes to life and begins to eliminate all competing restaurants in town. The restaurant's drive-thru speaker head then grows bigger, to where its' face morphs into an angry face, and when it catches Jimmy attempting to bring itself down, its' face grows angrier and attempts to shoot down Jimmy.
- How it destroys the competing restaurants, by disintegrating the buildings with a gun that spews out an orange acid-like substance. Fridge Horror kicks in as we see customers running away as the restaurant vanishes, meaning there might've been a chance people were still inside the restaurants.
