Anais from The Amazing World of Gumball. As a four-year-old who's smart enough to be in middle school, she's created her fair share of plans to get what she wants (such as tricking her whole family out of the house so she could watch TV, or changing the password on the computer to effectively lock Gumball and Darwin out). It's also clear that she inherited her mom's Hair-Trigger Temper, and she's prone to making creepy facial expressions. And that's not even getting into what happened when she tried to befriend her classmate Jodie...Oh, and did we mention that she spent most of her infancy trying to murder her brothers?
Parodied in American Dad!. In Rapture's Delight, After the End Stan goes to the headquarters of the Antichrist (which is the destroyed UN headquarters in New York), he sees a Creepy Child and immediately shoots it under the assumption it's the Antichrist. As Jesus tells him, that was just a normal kid who sometimes comes there to play. Oops.
Nemo, Hayley and Jeff's adopted son...who turns out to be the Antichrist himself in his infancy.
A 9-year-old Azula in a flashback episode of displays these traits, doing such things as burning a doll (a gift from her uncle), mocking her uncle's sorrow about his son's death, and hoping for his death as well as her grandfather's so her father can get on the throne. Her mother speaks for everyone when she wonders "What is wrong with that child?" Creepier than all of that together is her display of love for her brother:
Subverted with Lydia Deetz from Beetlejuice. In the movie, Lydia was a depressed "strange and unusual" child. In the cartoon, she's still strange and unusual but she's also sweet and creative.
The original Ben 10 series had Kevin. He was Ben's age, but highly sociopathic and his plans added up to "how can I kill the maximum number of people in my plan to get money/revenge?" He had all Ben's 10 original alien forms plus a hideous mashup of them that let him use all their powers at once, but it was creepiest when he was a kid and so pure evil. This is what made his (initially unexplained) HeelFace Turn between the original series and Alien Force so jarring: bad guys become good all the time, but he wasn't Ben's Catwoman, he was Ben's Joker.
Bob's Burgers has Gene and Louise. Gene is a relatively mild example, whose height of creepiness is wanting to slap a dead seal because it "sounds like an orgy". Louise, on the other hand, attempts to convince her father to kill a man with a knife, a cheese grater, a batter whisk, his credit card (which she cuts into a ninja star), and his own nose bones.
In one episode of The Boondocks, a 6-year-old boy named Lamilton Taeshawn in a taped therapy session describes, with a blank face, how he hurts people and states how he doesn't care if he killed any of them. When the therapist asks why does he do bad things, in a chilling confession he states "cause it's fun to do bad things." Things only got worse from there.
Darla Dimple from Cats Don't Dance who hides a psychopathic personality behind a sickeningly sweet child-like facade.
Numbuh Three's little sister Mushi at first comes across as being just as childish and ditzy as her older sister. However when she is stuck alone on the spaceship with Cree and Numbuh Five she gives a speech about how they should stop fighting, because sisters are supposed to care about each other and be friends. As the teenage villain stops to think about this, the little girl pushes her out the airlock, turns to Abby and says older sisters always fall for that mushy stuff. In her next appearance, her true colors are revealed as she stabs her sister's stuffed animal and is sent to her room forever. After that, she becomes a full-fledged villain and creates a spanking monster to attack kids.
It's strongly implied that Mushi's bad side really came out as a result of her hooking up with King Sandy, the little boy who tried to forcefully marry Mushi's big sister...twice. After Mushi gets grounded again for making the spanking monster, Numbuh Two witnesses Sandy helping her escape from her room.
The Delightful Children from Down the Lane are a more blatant example. They carry out the adults' evil orders, they never use their individual names (except the one with the red helmet, Lenny), and they're always speaking in unison. When Lenny joined back with the others, he just slides into his spot while a creepy, morphing sound plays, while he regrows his helmet. Ugh.
Youngblood from Danny Phantom. This is most prominent in his second appearance when he tries to behead Jazz with an axe, and later pushes Danny's parents down a waterfall.
Brittany Taylor's little brother Brian from Daria: he's a mean hyperactive brat who throws temper tantrums when he doesn't get what he wants, but the creepy thing about him is in the episode with the lab rats. Brittany steals Daria's rat and gives it to him, and he rubs his hands together and laughs wickedly. The next time we see the rat it's huddled in a corner and trembling; the guide book states that he's killed every pet that the family ever owned to the point where they stop bothering to name them.
One episode of Dexter's Laboratory, "Aye-Aye Eyes", features Dexter returning a creepy looking rag-doll bunny to an even creepier looking doe-eyed little girl who then follows him around everywhere. He eventually gets rid of her by hooking her up with a creepy doe-eyed boy.
Ducktales 2017 has Doofus Drake, a Spoiled Brat who inherited all of his rich grandmother's money upon her death and terrified his parents into becoming his Extreme Doormat servants, forcing them to do highly disturbing things. Louie's first encounter with the kid ended with him almost becoming trapped in Doofus' mansion and tortured into submission. Fortunately, he does get his comeuppance — in a later episode, his new adopted robot brother (long story) transfers half of Doofus' money into his own account, giving his parents the push they finally need to grow a spine and ground him indefinitely.
Ed, Edd n Eddy: Sarah. She is Ed's psychotic Spoiled Brat of a little sister, who acts cute and charming only when it serves her. Sarah has Ed's unending loyalty and obedience, mostly from her threats of snitching on him and her constant acts of physical violence against him. She has a short temper and is easily agitated by others, especially her brother and his friends and will often go on a violent rampage against anyone who annoys her or who bothers her best friend Jimmy. It's also implied that Ed's parentstreat him with emotional abuse, while Sarah is treated like a princess.
Edgar & Ellen: Edgar, and indeed, Ellen are a pair of extremely mischievous 12-year-old Creepy Twins who enjoy causing mayhem and trouble for the squeaky-clean, goody-two-shoes people of their town.
The three Fates of Gargoyles can appear as three creepy little girls (among other things), and make this creepier by turning into talking little-girl statues and then crumbling before the gargoyles' eyes. (In fact, they seem to be able to take the form of any female creature of any age; they can be lovely young women, demonic old hags... Whatever they want, so long as it's female.) They ARE the Weird Sisters of Macbeth, after all.
Li'l Gideon definitely counts. First he tried to cut Dipper's tongue out with lamb shears just because he thought Dipper was trying to get between him and Mabel, and in the first part of the two-part finale, he summons a dreamwalking demon to find out the location of the deed to the Mystery Shack! After he gets thrown in jail he sends letters to the Pines family. The letters themselves are pretty creepy, but the most unsettling part is the hidden message he put in Mabel's. By reading the capitalized letter of each new line you get this message
HELP ME ESCAPE OR BE DESTROYED
Although Mabel is normally as far from being creepy as is easily imaginable, her normal personality contrasts so much with her behavior while possessed in "The Inconveniencing" that it serves to make the moment even more unnerving than it normally would have been. She's also seen this way by some of the boys in the town, because she can be a bit too forward.
Dipper is a subtle version of this. He is very interested in the secrets and conspiracies involved with the town, even sometimes going out to actively capture monsters (Like in "Boss Mabel"). He will also seek out revenge on those he feel wronged him or his family/friends and will try and encourage his sister to do the same. By far the creepiest thing about him though is the unsettling coded message he puts in his certificate in Dipper and Mabel's Guide to Mystery and Non-Stop Fun.
By signing this official document, you are hereby agreeing to dedicate your life, your afterlife, and any potential clone-lives to the discovery, uncovery, and exploration of the paranormal, the alter-average, and the extra-usual. When friends ask you to stop being paranoid, you will scoff. When they say that youve been acting really weird since you read that book and they dont even recognize you anymore, that means theyre jealous/you are like me now. We are part of a higher calling. We will meet one day and on that glorious day we will show the small-minded doubters we were right all along, and are also really cool, and they should have been nicer to us. Okay thats about it. This sort of sounds like a supervillain manifesto in retrospect. But you get the gist.
Mandy is an eponymous character and a merciless, cynical girl. She tricked The Grim Reaper into eternal servitude, using him as her maid and his powers for personal gain, and faces down everything from the Boogeyman to Cthulhu with nothing more than a wry comment. She also never smiles, ever, because doing so would cause the universe to implode. She was also able to take over a large evil brain/alien when it ate her brain.
Then there's Nergal Jr. Nergal Jr. is able to turn into almost anything and is extremely creepy. His true form (although it's rarely seen) is very horrid to see.
Creepie Creecher, the protagonist of Growing Up Creepie, is a young girl raised by insects. She is a junior Goth in style, and her creative efforts regularly terrify her teachers and schoolmates. Things like ghost stories and urban legends merely arouse her curiosity, usually leading to her debunking them (usually followed by an Real After All twist that only the audience sees).
Hey Arnold!: Curly and his Troubling Unchildlike Behavior sometimes comes to the point of high-potential Ax-Crazy. For example, upon finding that he wasn't assigned the Ball Monitor privileges that he anticipated for that week, he holed himself up in the principal's office with the balls, throwing them at anyone who tried to reason with him. There was also the episode "False Alarm" where he tried to get Eugene expelled simply because he ruined his favorite pencil. And one episode mentions that he once bit off the head of a live chicken, though he insists it was only that one time.
Gaz of Invader Zim is a morbid, vindictive little girl with supernatural powers and prowess who plunges people into nightmare worlds from which there is no waking if they dare interfere with her pizza or her video games. Not even her brother is immune. Her ''father'' is, though.
Not to mention the ROBOT CANNIBAL STUFFED ANIMAL SECURITY SYSTEM.
Ace from the first-generation Royal Flush Gang in Justice League ("Wild Cards" arc). Just looking at her can make you go insane. Even if you already are; ask the Joker. She turns into the most dangerous, frightening TheWoobie Woobie you've ever seen in the JLU episode Epilogue when you learn herbackstory. But for all the scary, you still want to hug her.
Mr. Cat from Kaeloo. He's confirmed to be less than 13 years old (though his exact age is unknown), yet he's an Ax-Crazy psychopath whose favorite hobby is to repeatedly kill Quack Quack the indestructible duck with various weapons. One of the most notable examples in the show is in the episode "Let's Play Magicians" where he dances around singing "la, la, la" while sticking knives into Quack Quack's body.
The episode of The Little Mermaid the animated series "Island of Fear" featured a mad scientist with a lab assistant, a very creepy young boy named Daniel. Sebastian even screams the first time he meets him, but as it turns out he's not really evil, just misunderstood; he doesn't have many friends and he took the job because his parents were poor.
The Loud House: Lucy Loud certainly fits the bill. She voted to spend a vacation at the beach in hopes of seeing a shark attack; she suggested buying twin burial plots for their parents' anniversary, reasoning "Nothing says romance like eternity"; and according to her parents, she apparently didn't cry much as a baby and the reason they let her bangs grow to cover her eyes is because they found her staring to be creepy. However, she does have a good heart under her creepiness and cares a lot about her family.
Cozy Glow is revealed to be even worse than Diamond Tiara in "School Raze" - she works with Tirek, who is himself one of the most evil and sinister villains on this show, she traps Mane 6 and Spike in Tartarus, which is pretty much the show's version of Hell and uses various magical artifacts to trap Starlight as well. She does all of this to become the "Empress of friendship". And this is all something that a filly who is around the same age as the Cutie Mark Crusaders did.
Some say that Suzy Johnson, Jeremy's little sister on Phineas and Ferb, is the true villain of the show. And who can blame them? As Jeremy's self-proclaimed "favorite girl", Suzy resents her brother's relationship with Candace and constantly puts the hurt on Candace when no one else is looking... and thus, no one believes Candace when she says that Suzy is evil. Buford Von Stom is the only other character on the show who knows what Suzy is really like (no one believes him either).
The titular character of Ruby Gloom plays with this. While Ruby is a pale 10-year-old girl living in a house of horror-esque monsters, all of which are her friends, she is very kind and friendly, as are said monsters.
3-year-old Angelica, while seemingly polite and sweet to adults is actually a Spoiled Brat and a Control Freak who more often than not abuses her baby cousin and his friends. Though there are rare moments where she is nice to them. She also has a tendency to root for and sympathize with those who are clearly villains...
Even worse is Angelica's baby brother from her nightmare in the episode, "Angelica's Worst Nightmare".
The Sam & Max: Freelance Police episode "The Trouble With Gary" features the duo looking after a child with demonic powers, and whenever he got angry he would transform people into things or smash stuff with his mind. Eventually the two are able to get him to control his anger. By which we mean, "reduce his attention span to rubble", preventing him from focusing on people that annoy him long enough to use his powersnote And also rendering him indistinguishable from an ordinary little boy, to the joy of his parents.
In the episode "Wild Barts Can't Be Broken," the kids all break curfew to see The Bloodening — a parody of the horror film Village of the Damned (1960) — featuring sinister telepathic and telekinetic children terrorizing an English village. When the kids of Springfield are punished for sneaking out, they get revenge by hijacking the radio airwaves and, speaking like the Creepy Children of the film, broadcast their parents' embarrassing secrets.
"We've got to do something about these blabbermouth kids and their creepy English accents!"
"Doctor, we know you and the bootblack have been rogering the fishwife in the crumpet shop!"
Another episode featured a horror film starring Lenny Leonards as a gardener called The Redeadening, which not only draws elements from Village of the Damned (1960), but also Child's Play (a demon-possessed doll) and Coraline (victims having their eyes replaced with buttons) as well.
Lenny: It looks like if the buttons are sewn onto my eyes, but they're actually held up by hot wax.
Bart himself becomes one of these in "The PTA Disbands" when the teachers strikes lasts too long. There's something about flying a kite at night that's so unwholesome...
There are a few, including Kenny. Then there's Damien from the episode Damien - after all he's Satan's kid.
Cartman; ever since the Scott Tenorman incident he's become increasingly psychotic throughout the years, going as far as attempting to kill his mother when he feels she doesn't love him anymore. Even Damien McSatan thinks there's something wrong with Cartman.
Onion. He has no ears and almost never speaksnote you could count the number of episodes where he does speak on one hand, and he's The Unintelligible like his father Yellowtail. He tends to throw away food instead of eating it, and sometimes puts it in his mouth and lets it fall back out. Steven isn't sure if he's even human. The entirety of "Onion Trade" is rather creepy because of him, where he's more of an Enfant Terrible, stealing things, throwing away food, crashing a scooter which burst into flames, and nearly destroying Beach City using a replicator wand because he was bored and lonely. He shows some good traits in "Onion Friend" (getting Vidalia and Amethyst to hang out again, giving Steven one of his GALS capsule toys) but he still is said not to eat, makes a mashed potato sculpture of Steven's head, licks it, and spits it out, shows Steven a video of his birth, and lures Steven into a secret passageway which Steven is very reluctant to do (though it ends well). Finally at the end of the episode he opens his mouth and the mouse he was going to feed to his pet snake comes out. Other episodes feature him committing various crimes, up to and including arson, and Steven is concerned that Onion might wind up in prison. In the Steven Universe: Future episode "A Very Special Episode", Steven has to temporarily leave Onion in Pearl's care; she discovers that Onion has a bag of human hair, and things go downhill from there.
Pearl (frantically, about Onion): I can hear him... but I can't see him. I think he's in the walls, and I don't know how to get him out!
Pink Steven, the Steven that forms out of Steven's gem when it's removed from his human body. While Human Steven retains his personality but none of his power, Gem Steven retains all of his power but none of his personality. As a result, except for when he in the process of fusing again with Human Steven, his face remains completely expressionless throughout, even when he's screaming at the top of his lungs at White Diamond, loud enough to smash a giant crater into the concrete floor. He No-Sells White's attacks, even nonchalantly turning White's power back onto the possessed Diamonds and Crystal Gems, flinging them all across the room. This is a Steven without any compassion, love or care for others, a completely ruthless machine with a singular goal, to reunite with Human Steven, and no qualms about hurting those he loves in order to reach it.
The baby from Tin Toy, due to a major case of Uncanny Valley. He/she behaves like an ordinary baby, though (not that that isn't distressing to the toys).
Dawn from Total Drama Revenge of the Island, as she manages to creep out several contestants with the freaky ability to read their auras, including Zoey, Dakota, Lightning, and Scott. Lighting even refers to her as a "Creepy Girl". However, Dawn isn't malicious at all, and is in fact a very sweet and gentle character.
On Total DramaRama, Gwen is recharacterized from a Perky Goth to this. She carries with her a headless doll, enjoys scaring the other children or watching them get harmed, often makes ominous statements about death and misery, and likes to dress as a bat and hold funerary services.
Frances is a middle school girl who does nothing but say "I like pointy things" while her eye twitches. According to a flashback, she used to be a kid genius who was friends with Tish, before her sudden decline into... whatever it is she's suffering from.
The final episode of The Weekenders shows how frightening Todd and Quintie can really be. Apparently, they're threatening enough for the S.W.A.T. team.
W.I.T.C.H. has Miranda, a shape-shifting spider demon who takes the form of a little girl. Often uses her human child form to trap and trick her prey and enemies, but still manages to keep her creepy spider attitude.