History NightmareFuel / TheAdventuresOfJimmyNeutronBoyGenius

** 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. [[MoodWhiplash And THAT'S]] [[ComicallyMissingThePoint why they call him Betty!]]

* The Twonkies. Indestructible, vicious, and downright ravenous little 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.
* ''Flippy'' turns out to be pretty dark considering it's Slappy from the R.L. Stine Goosebump series UpToEleven. To explain, 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. [[EvilHasABadSenseOfHumor Not to mention joking about how he took Hugh's brain, planned on marrying Jimmy's mother, and skipping town to go to Las Vegas.]] When Jimmy caught on, Flippy threatened to destroy Hugh's brain since he controlled Hugh's body. When he gained full sentience, 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.

** Cindy being strangled by a boa is PlayedForLaughs but her pale white face, bulging eyes and overall terrified expression make it look like she really ''is'' about to die.
** the giant spider [[FromBadToWorse (especially if you have arachnophobia)]].

* 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, that looks like a giant lightning spewing jellyfish, that laid the egg comes all the way to Earth to look for its baby!

** [[DontExplainTheJoke For anyone who's still confused...]] Betty intends on [[TheBait using Jimmy as bait]] [[spoiler:to lure out the Lake Monster]]. [[FridgeHorror A crazy old man was willing to kill a child to catch something that for all anyone could know doesn't even exist]].

* ''Flippy'' turns out to be pretty dark considering it's Slappy from the R.L. Stine Goosebump series UpToEleven. To explain, Hugh purchases a puppet named Flippy to practice ventriloquism but his comedy is lacking, so Jimmy puts a computer chip in Flippy's head to enhanced Hugh's brain. Instead, Flippy uses the chip to draw power 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. [[EvilHasABadSenseOfHumor Not to mention joking about how he took Hugh's brain, planned on marrying Jimmy's mother, and skipping town to go to Las Vegas.]] When Jimmy caught on, Flippy threatened to have Hugh harm and even kill himself since he controlled Hugh's body. When he gained full sentience, 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 has some minor control over Hugh's mind.

* ''Flippy'' turns out to be pretty dark considering it's Slappy from the R.L. Stine Goosebump series UpToEleven. To explain, Hugh purchases a puppet named Flippy to practice ventriloquism but his comedy is lacking, so Jimmy puts a computer chip in Flippy's head to enhanced Hugh's brain. Instead, Flippy uses the chip to draw power 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. [[EvilHasABadSenseOfHumor Not to mention joking about how he took Hugh's brain, married Jimmy's mother, and planned to skip town to go to Las Vegas.]] When Jimmy caught on, Flippy threatened to have Hugh harm and even kill himself since he controlled Hugh's body. When he gained full sentience, 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 has some minor control over Hugh's mind.

* ''Flippy'' turns out to be pretty dark considering it's Slappy from the R.L. Stine Goosebump series UpToEleven. To explain, Hugh purchases a puppet named Flippy to practice ventriloquism but his comedy is lacking, so Jimmy puts a chip in Flippy's head to enhanced Hugh's brain. Instead, Flippy uses the chip to draw power 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. [[EvilHasABadSenseOfHumor Not to mention joking about how he took Hugh's brain, married Jimmy's mother, and planned to skip town to go to Las Vegas.]] When Jimmy caught on, Flippy threatened to have Hugh harm and even kill himself since he controlled Hugh's body. When he gained full sentience, Flippy planned to kill Hugh by chucking his body off a cliff so Hugh couldn't get his brain back.

''Flippy'' turns out to be pretty dark considering it's Slappy from the R.L. Stine Goosebump series UpToEleven. To explain, Hugh purchases a puppet named Flippy to practice ventriloquism but his comedy is lacking, so Jimmy puts a chip in Flippy's head to enhanced Hugh's brain. Instead, Flippy uses the chip to draw power 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. [[EvilHasABadSenseOfHumor Not to mention joking about how he took Hugh's brain, married Jimmy's mother, and planned to skip town to go to Las Vegas.]] When Jimmy caught on, Flippy threatened to have Hugh harm and even kill himself since he controlled Hugh's body. When he gained full sentience, Flippy planned to kill Hugh by chucking his body off a cliff so Hugh couldn't get his brain back.

* The Twonkies.

->'''Betty:''' Gadgets go in the water! You go in with the gadgets! Monster in the water. ''Our'' monster.\\

* The DNA Productions logo screen at the end of every episode doesn't help much. A theme music similar to an OminousMusicBoxTune plays, and then a 3-eyed monkey jumps out, looks at the screen, and says (in a weird, squeaky voice) "HI! I'M PAUL!" It can be slightly disturbing for some viewers.

** Don't forget forget to mention Johnny Quasar, the first ever Jimmy Newtron short. It's much more deranged and creepy.

* "Nightmare in Retroville", appropriately enough for a Hollywood special, has plenty of this. Jimmy's monster machine that he created in an attempt to make his friends look like monsters for Halloween actually turned them into monsters, complete with bloodlust, by mutating their molecular structure on a subatomic level and altering their DNA. As such, both Carl and Sheen become bloodthirsty monsters, hell bent on killing or turning others into monsters themselves:

** Brain!Sheen in general is a big KnightOfCerebus, courtesy of WithGreatPowerComesGreatInsanity as he develops PsychicPowers and {{Sociopath}}y the more his head grows -- to the point where he even nearly kills "Ultra Lord" (actually a disguised Jimmy and Carl), his lifelong idol, for trying to revert him to normal.

* "The Evil Beneath" is actually full of this. The plot follows Jimmy and his friends investigating to find the reason behind the string of boats and planes that disappeared in an area of the sea known as the Bahama Quadrangle. When they get there, they find Dr. Sidney Moist, one of Jimmy's scientist role models and leading researcher in phyto-chemicals compounds thought long dead. Though he comes off as a silly and goofy weirdo who likes dancing, 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. After they destroy the lab and think they solved the mystery, a dense fog appears out of nowhere with multiple pairs glowing red eyes inside the fog (implied to be evil porpoises based on the screeching from the fog) and Jimmy and the gang decide to leave the mystery unsolved before fleeing away in terror.

* "The Evil Beneath" is actually full of this. The plot follows Jimmy and his friends investigating to find the reason behind the string of boats and planes that disappeared in an area of the sea known as the Bahama Quadrangle. When they get there, they find Dr. Sidney Moist, one of Jimmy's scientist role models and leading researcher in phyto-chemicals compounds thought long dead. Though he comes off as a silly and goofy weirdo who likes dancing, 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. After they destroy the lab and think they solved the mystery, a dense fog appears out of nowhere with glowing red eyes inside the fog (implied to be evil porpoises based on the screeching from the fog) and Jimmy and the gang decide to leave the mystery solved before flying away in terror.

* ''The Evil Beneath''is actually full of this. The plot follows Jimmy and his friends investigate to find the reason behind the strong of boats and planes who disappeared in an area of the sea known as the Bahama Quadrangle. When they get there, they find out Dr. Sidney Moist, one of Jimmy's scientist role models and leading researching in phyto-chemicals compounds thought long dead. Though he comes off as silly and goofy weirdo who likes dancing, 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 spies 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.

* ''The Evil Beneath''is actually full of this. The plot follows Jimmy and his friends investigate to find the reason behind the strong of boats and planes who disappeared in an area of the sea known as the Bahama Quadrangle. When they get there, they find out Dr. Sidney Moist, one of Jimmy's scientist role models and leading researching in phyto-chemicals compounds thought long dead. Though he comes off as silly and goofy weirdo who likes dancing, 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 spies sent to spy on him. He's done this many times and would have successfully done it to Jimmy and his friends.

* "Nightmare in Retroville", appropriately enough for a Hollywood special, has plenty of this:
** Carl cuts his finger, starts sucking on his blood and actually ''enjoying'' this (because he's just starting to become a real Dracula), much to Jimmy and Sheen's disgust and confusion.

[[quoteright:350:http://static.tvtropes.org/pmwiki/pub/images/paul_2.jpg]]
[[caption-width-right:350:Hi, I'm Paul!]]

* The DNA Productions logo screen at the end of every episode doesn't help much. A theme music similar to an OminousMusicBoxTune plays, and then a 3-eyed monkey jumps out, looks at the screen, and says (in a weird, squeaky voice) "HI! I'M PAUL!" Never failed to be disturbing.
** Becomes NightmareRetardant when you see the different versions of the Paul logo. There's one where he says "...so what do you want me to say now?", one where he calls for line, one where he says his name in Spanish (with a mustache!), and one where he doesn't appear at all (with a single "huh?" heard in the background).

** the giant spider.
* The Nanobots proceeding to delete everyone from existence due to them being "flawed". If Jimmy hadn't intervened before they hit the "empty recycle bin" option...

* Jimmy being reduced to a gelatinous slab after running around too fast. His body will eventually re-stablize into solid matter.