In the mid-2000s a creepy little girl appeared on several shows including CSI, Law & Order: Special Victims Unit, Close to Home and The Inside. Despite going by different names and having different mothers on each of them, she always acted the same and was always played by the same actress Jennette McCurdy (who later went to iCarly). She would always pretend to be a Cheerful Child that just happened to have overheard or seen damming evidence against a person that implicated them as a murderer; however it always turns out that the little bitch was lying to them and the person she claims did it was completely innocent, just convenient patsies which were easy to frame. After proving her story was bull the police would confront her about it and she would try to blame somebody else. About half the time it wouldn't work, and they exposed her as the Enfant Terrible she really was. The other half they went after the second person she blamed for the crime and arrested them not even suspecting that the little girl was actually a murderess.
Jennette McCurdy got roles in several Nickelodeon kids' shows playing the same character, except that around other kids she seemed less creepy and more simply violent. She once said in an interview that the reason she liked playing this type of character was because it was so different from who she actually was in real life.
Ari Graynor was on an episode where her younger sister was shot in a video store robbery. Then we learned she arranged for the sister to be molested and then killed to prevent her talking. The explanation was that she was an abused child and a total sociopath. When they got her she said "You think I'm scared of the death penalty? You can't kill me - I'm already dead." Brrr.
In one episode of SVU, a ten-year old boy targets a younger boy he used to play with at a birthday party and after kidnapping him kills him by forcing him to consume rocks. Once he is implicated in the murder, it is implied he had been abused sexually and physically while at summer camp. When Detectives Stabler and Benson investigate, they find out the boy taunted many of the children he went to camp with, was prone to picking fights, and would injure himself to gain sympathy from the adults, and so most children actually avoided him completely. He is revealed to be an undiagnosed sociopath, having absolutely no sympathy for his actions or even any reason for wanting to kill the younger child other than he felt like it. When the boy's distraught father, a child psychologist lashes out at him for his actions the boy feigns sympathy and taunts him further. Convinced he'd kill again once he was released from juvenile custody, the father shoots him dead in front of the police, justifying his actions on the belief that the kid was beyond all help.
Sunny Capaduca from 15/Love was a scary little girl with a heavy nearly untraceable accent, Jerk Jock and Manipulative Bitch tendencies, and a liking for frightening the other (much older) kids at the school. She stopped just short of being an Enfante Terrible.
Wednesday and Pugsley Addams from The Addams Family, although it's played for laughs here.
American Gothic (2016) has Jack. While not a suspect in the serial killings done by a member of his family, he is seriously creepy. He is obsessed with death and his actions Torturing the neighbor's cat, throwing a toy on a tarp covering a pool to trick his young cousin to go out on it and drown make you shutter for the future of the family.
Wolfram & Hart's conduit to the Senior Partners in Angel was a little girl. And she was also the dark reincarnation of Ra, representing the sun at sunset and the evil of humanity.
There is also an episode revolving around a creepy child possessed by a demon that corrupted the souls of those it possessed. When they exorcised the demon they learned that it hadn't been controlling him, but had possessed him and been trapped inside by the soulless child.
Asia's Got Talent (and America's Got Talent afterwards) introduced "The Sacred Riana", a young stage magician with some decidedly sinister acts. Her stage persona (which she never seemed to break, even after the acts were done) involved wearing an old-fashioned school uniform, having hair hanging over her face, constant twitching, and never speaking other than making sinister utterances and unintelligible spells. The judges were terrified of her, especially since her acts involved placing pentagrams on their hands, appearing as a ghost in photos she took herself, and summoning far too many zombies out of a box painted like the Lament Configuration. On the other hand, she received nothing but praise and ovations, leading up to winning the whole thing.
On Believe, Bo Adams is a little girl with psychic powers that often manifest in scary ways.
Yandere Rhonda Vollmer on Big Love is a non-supernatural variant: behind her artless demeanor and expressionless blue eyes lurks the brain of a baby sociopath and master-manipulator-in-training (and a disturbing fondness for rhinestones). She's got something of an excuse, having been raised in an abusive cult and married off at the age of fourteen to a man in his seventies, but it doesn't do much to make her less terrifying. (Amusingly, she's played by Daveigh Chase, who portrayed the ultimate Creepy Child in the American version of The Ring.)
Buffy the Vampire Slayer had The Anointed One. In a typical Joss Whedon moment, however, when Spike shows up he takes "The Annoying One" down within an episode. (According to rumour, he was killed off because the actor was growing too rapidly for a dead kid.)
"Gingerbread" features two murdered children (later revealed to be Hansel and Gretel themselves) who appear as ghosts and force the Brainwashed and Crazy town to try to kill Willow, Buffy and Amy.
"Hush" opens with Buffy dreaming of a spooky little girl, complete with the nursery tune. What makes the girl spookier is that she looks like a kid-version of Buffy.
The Closer has Skander Marku from the Season 6 Christmas two-parter, who acts unnaturally calm and almost smug amidst his whole family ending up dead. He appears to care more about his dog than the fact that his home is a crime scene, smirks at the cops when his (newly-met) aunt and uncle take him home, and when arrested, makes up a patently false story of how the arresting officer tied him up and threatened him. Subverted in the second half; when he's told that all the family he knew about had been killed, he breaks down crying. His odd behavior at the police station was most likely due to his family's mistrust of the police; he acts more like a normal child after he realizes that the police are trying to protect him.
While not creepy in a supernatural sense, Insufferable Genius Hannah from a two episode "arc" of CSI definitely qualifies. In her first episode she helps get her brother out of a murder conviction by convincing the jury that she did it, while gaining CSI Sara Sidle's sympathy (she was also a gifted child), only to smugly reveal to her that her brother did indeed set up the prank and that she's going to get a lot of book deals once she's out of juvie. In her second episode the two siblings are in college (their parents are mysteriously dead), with the brother as a student and Hannah as his professor. Several plot twists and one Breaking Speech at Sara later, it is revealed that Hannah had begun to envy of her brother's growing independence and framed him for murder in order to put him in jail, under her control and at her side forever. Her brother could no longer stand his sister's truth-destroying plans and killed himself and "arresting officer" Sara was simply disgusted, which probably contributed to her eventual two season leave of absence.
The entire X7 series from Dark Angel. Scary mute child soldiers, with a unit hive-mind, the ability to communicate with each other ultra-sonically and freaky goddamn black eyes. The X8 series, however, seems to be identical to the X5 and X6 series, bizarrely.
It was mentioned in the novels that finish the film that after the experiments became stable (X5) each series was designed for specific goals in mind. The X5's are boosted with feline DNA and were used as commandos. The X6 are similar but either due to genetics or training are much less independent. The X7 seemed to have been designed to work as squads, given their abilities they were most likely meant for a more straight forward attack style. The X8 were never shown in combat (only one was seen on the show), maybe the X7's scared the military or they only needed one group with those specific abilities? There's also the anomalies, failures that were occasionally used for very specific goals (lizard man Mole apparently helped kill Saddam while a blue guy he argued with was involved in some mission in the Arctic).
Ally from episode two of Demons who kidnaps children for Gilgamel.
Dexter was one of these as a child, killing animals and getting though a psych test only by answering the opposite to what was true.
"Fear Her": Chloe Webber is a rare example of a black Creepy Child. She's been possessed by an alien with the power to trap people in drawings, and they are using this power to cause children to disappear.
"Human Nature"/"The Family of Blood": Sister of Mine, who always carries a bright red balloon. It never pops. Odd. Most likely a reference to the original book, in which the little girl's balloon behaved like Rover. When either girl appears on screen, they also have the same Ironic Nursery Tune. And what happens to her in the end will make you afraid to look in mirrors.
"The Sound of Drums": The 8-year-old Master. Russell T. Davies noted in the script that the child should be "Damien-like". Keep in mind we only see him for a very brief scene as he looks into the Time Vortex. Kudos to the actor, managing to creep us out with a few seconds of standing there looking at the camera, no lines spoken or actions taken.
"The Eleventh Hour": Shapeshifting Prisoner Zero in the form of 7-year-old Amelia Pond, who spends its time in that form mocking the real Amy.
"The Beast Below": A little girl appears in a recording reciting a creepy nursery rhyme just before an unfortunate boy is dumped below to become fodder for the Beast.
"The Lodger": One of the forms taken by the AI of the time engine luring in people to try and find a new pilot is a little girl with her Face Framed in Shadow at all times.
Doctor Who Magazine comic strip "Ghosts of the Northern Line" has Monster of the Week Mnemosyne take on the form of a little girl ghost, who at one point stands on the tracks in front of a tube train, prompting the driver to slam the brakes on giving the other ghosts time to feed on the living.
Dotty/Kirsty Cotton from EastEnders. She was a little girl of no older than nine or so, seemingly dumped on her grandmother Dot by her criminal father Nick. At first she seemed saccharine sweet, but it soon became clear that something was wrong. Her hymn-singing, baking, little 1930's cardies and general innocence took her beyond the realms of 'normal but goody-two-shoes kid' and into the realms of creepy. You could tell she had to be hiding something - and she was. Turned out she had a pact with her Father Nick to kill Dot for her money, and it didn't seem like she was being threatened by him or otherwise coerced into it; she appeared to be doing it willingly, off her own back. She pressed on with this plan until the last minute, when she got cold feet and attempted to drug Nick instead. Nick survived, but as he left he shouted not to be fooled by Dotty's traumatised tears: she was rotten to the core and the plan to kill Dot had been all her idea. It sounded like a bitter rant, but this is EastEnders we're talking about, so there will almost definitely turn out to be some truth to his words.
River in Firefly can approach this at times, though usually her Woobie-ness overrides the creepy elements. She's also somewhat older than the typical Creepy Child, though her behaviour tends to be very childlike.
FlashForward (2009) has Charlie, who has an unspecified vision that she simply (and in monotone) describes as "dreaming that there were no more good days".
Robin Arryn. "Mummy, I want to see the bad man fly." The fact that his crazypants mother is still breastfeeding him at age EIGHT or so doesn't help. When he returns in season 4, the first thing he does upon meeting Sansa is to bring up her family's horrible deaths at the Red Wedding, in a tone that would be better suited a discussion of the weather. He maintains the same calm demeanor when explaining that his own father was poisoned.
By Season 3, Arya Stark is starting to rapidly become a Creepy Child in her own right, though not nearly as quickly as in the books. She's reached this completely by Season 4; Melisandre of all people is creeped out by her. To recap some instances of her coldness:
She declares Death to be her one true God.
In "Mhysa", she walks up to a group of Frey men around a campfire who are mocking Robb and Cat's demises. Arya acts like an innocent child, asking if she can warm herself by the fire, even offering to pay. She casually drops the coin, and when the man leans to pick it up, she stabs him repeatedly in the neck with a dagger. When she's done she doesn't seem at all disturbed by what she just did.
She calmly informs Sandor Clegane that she will put a sword through his eye and out the back of his skull someday. Later on she turns out to actually have a knife she got from him without him noticing. His reaction is priceless.
In "Two Swords", she calmly and methodically taunts Polliver before sticking Needle through his neck, clearly enjoying the deed.
In "Mockingbird", she notes Rorge was never on her list of people to kill because she didn't know his name. When he gives it to her, she thanks him with a little smile, then stabs him through the heart.
In the Season 4 finale, the Hound begs her to give him a Mercy Kill after being badly wounded, trying to provoke her into anger but she just crouches and stares at him icily for a very long time... before robbing him and leaving him to die.
The show seems to have ultimately subverted this, however, thanks to the timing differences. Show!Arya has reached her mid-teens before she could slip fully into the Creepy Child territory.
Jojen Reed comes across as a bit of this—his Greensight contributes to this—but he's really very nice once you get to know him. He can invoke this to threatening effect though, like when he intimidates Karl Tanner right as he's about to rape his sister Meera.
The reanimated child corpses in the Battle of Hardhome.
The child wight in "Winter is Coming" is creepy enough to provide the trope image for Occult Blue Eyes.
In "The Pointy End", after disappearing for several episodes, Rickon Stark suddenly appearing in Bran's room and making a deadpan declaration that his family won't come home is very unsettling. He also spends the time he is forced to hold court with Bran in Winterfell cracking nuts in the most aggressive way possible. He also wanders off on his own several times with Shaggydog.
Bran himself gets quite unnerving after becoming the Three-Eyed Crow. He even creeps out Littlefinger.
The assassin sent by the Warlocks of Qarth in "Valar Dohaeris" looks like a little girl, but has blue lips and hisses like a snake.
Subverted by Shireen Baratheon, who has a disfigured face and is introduced singing an eerie song but quickly shows herself to be a perfectly sweet little girl, despite having no friends and living inside a tower.
Madison from Harper's Island. She tends to creep out her mother late at night by waking her up and telling her everyone is going to die.
And the Chase-substitute kid on the plane from "Airborne" who thinks it's cool that he will have to help House operate on someone. The look on the face of the Cameron-substitute next to him seals it.
Chip Chambers from iCarly. He's a vicious kid and extremely loyal to his older brother, Chuck. When Spencer sends Chuck to military school for ambushing him, Chip mercilessly takes his anger out on Spencer... and the kid is only 9 years old.
Jam featured a sketch about a six-year-old hired "cleaner"/killer, Maria. She looks like an adorable little girl but carries a gun, swears continually and is very proficient in chopping up bodies. When one of them turns out not to be dead, she shoots him in the head and then carries on cutting him up. The radio series featured even more sketches about Maria, in which she was only four years old, and was revealed (among other things) to have a penchant for killing farm animals.
Two of the creepiest girls ever seen on TV were in the Law & Order episode "Killerz", which was Green's second case. The older one had a strange look and behaved in a way that just seemed off, however she was innocent and the way she acted made sense after you found out what her little friend had done. The younger girl at first seemed like a Cheerful Child that was better adjusted then the older one, however it turned out she Does Not Like Men and was a sociopathic Serial Killer of little boys. What makes her especially scary is that despite Dr. Skoda's diagnosis Dr. Olivet actually defended the Enfant Terrible and was able to get her off. As she was leaving we see the murderess eyeing her next victim: a very scared little boy.
In the first episode of the series' ninth season (and the debut one of Angie Harmon as Abby Carmichael), a rich couple's 7-year-old very disturbed adoptive kid was accused of killing his also adoptive baby sister. He didn't.
Elle Fanning played a creepy/disturbed kid in "Cage". Detective Dani Beck takes home the little girl who was from an abusive foster home. That night the girl wakes her up because she can't sleep, and Beck finds the girl has set fire to the curtains in an attempt to kill them both so they can be together.
Elliot Stabler's replacement, Amaro, was forced to confront a pre-teen sociopath named Henry while he held another child to him and pointed a gun at his head. Henry's other deeds included drowning a neighbor's dog, tying his little sister to a bed and setting her trash can on fire in front of her, threatening his mother with a knife before slicing her hand when she went to remove it from him, and slyly telling Detective Rollins that she's really pretty. Although at the end of the episode it is determined that Henry must be remanded to a mental health center for extremely disturbed young people, he tearfully tells his parents that he loves them (something he never, ever did before) which means they will probably always forgive his behavior.
Walt on Lost generally seems like a normal kid, but also has the habits of appearing in places he shouldn't be, knowing the future, and smacking birds into nearby windows. He manages to creep out his stepfather to the point of relinquishing custody. Then in season 2, he scares the Others enough that they give him back to his father.
The Mentalist has Haley in the 4th season episode "Red Rover, Red Rover" who approaches Jane in the middle of a cemetery to deliver him a message from Red John.
She's redeemed of creepiness though, when it turns out she was lured there and had no idea she was acting as messenger for a deranged serial killer.
Millennium has Jordan Black, Frank's younger daughter. She has powers similar to Frank's except they manifest themselves as metaphorical dreams.
Mystery Science Theater 3000: In the "Parts: The Clonus Horror" episode, Pearl runs into a band of creepy, reality-warping "Space Children" who proceed to pester her, Bobo, and Brain Guy.
The Outpost has Ilyin, the girl who accompanies Ambassador Dred everywhere. She never speaks, rarely blinks, her eyes are lightly discolored, and everything about her body language is just wrong.
In Person of Interest, a flashback shows the death of Shaw's father in a car accident when she was a child. The firefighter tries to explain that he's fallen asleep and will never wake up, to which Shaw calmly responds he means "dead". She then calmly asks for a sandwich as she's feeling hungry.
Season 4 introduces Gabriel Hayward, a Child Prodigy ten year old boy acting as an Analogue Interface for Samaritan. Relaying the A.I's words in Creepy Monotone and acting utterly indifferent to the claims it makes, Gabriel comes across as quite disturbing.
Both lampshaded and played straight in Stephen King's four part movie Rose Red: There's the classic and indeed creepy ghost girl April and then there's Annie Wheaton, one of the team of explorers in the haunted house. She's mostly a sympathetic character but slightly creepy due to being autistic screen as well as, among other things, telekinetic. At one point another (much less sympathetic) explorer calls her "that creepy child with that creepy doll". By the way, both Annie and April have their own theme music, but Annie (whose theme is a rather nice big band song) soon picks up April's creepy nursery rhyme theme.
Oscar from The Sarah Jane Adventures episode "The Temptation Of Sarah Jane Smith". At the end of Part One he turns out to be a Graske in disguise.
Susperia in "Cold Fire", being an incredibly powerful alien from another plane of existence who is trying to get Revenge on Voyager—and takes the appearance of a little girl.
The Borg children on their first appearance, being Borg.
A nightmare version of Naomi Wildman (usually an ordinary nice kid) in "Dark Frontier."
Kes, kind of, being physically adult but very innocent (thanks to her species' culture and Bizarre Alien Biology) sweet, and understanding. Except for a couple of times when her latent psychic powers get a little scary.
Worf was the first to discover the "imaginary friend come to life" when he ran into her and the little girl on a security patrol.
Tina from Still Standing is pretty creepy with her unblinking stare and vindictive nature. Her aunt Linda and older sister Lauren are particularly wary of her.
In Supergirl, a scary kid turns out to be J'onn's traitorous brother Ma'alefa'ak. He sometimes continues to take that form even after we know who we're really looking at. You gotta admit nobody would ever suspect...
"The Benders" has a thirteen year old cannibal named Missy.
"Playthings" has a creepy girl ghost manipulating the daughter of the owner of an inn.
"All Hell Breaks Loose Part 1" has an Acheri demon appear as a little girl◊.
"The Kids are All Right" has changeling children feeding off mothers' synovial fluid.
"Bedtime Stories" has Callie, a little girl ghost who's actually the restless spirit of a comatose woman and who is forcing innocent people into reenacting brutal and violent versions of the Brothers Grimm stories.
"Are You There, God? It's Me, Dean Winchester" has two little girls terrorizing Bobby.
Season Four's "The Rapture" has Claire Novak possessed by the angel Castiel informing Castiel's previous host (Claire's father Jimmy) that his (Jimmy's) work on Earth is done while poor Jimmy begs to be possessed instead.
The episode "Family Remains" has this in the form of a feral, in-bred child and her brother who torment a new family that moves into their house.
Though it's played straight then that same child returns several years later in "Season's Beatings" and that time he really IS the anti-christ.
Lampshaded in the season five episode "The Real Ghostbusters": "Oh look, more creepy children brought to you by Supernatural."
In "Nightmare as a Child", Markie is a strange, demanding child with a deadly serious manner. She tells Helen Foley that she knows every detail of her life. It turns out that Markie, a manifestation of Helen's Repressed Memories concerning the murder of her mother by Peter Selden, has good intentions but she is still creepy.
In "It's a Good Life", the six-year-old Anthony Fremont has extensive powers which allow him to read people's minds and make those who are not thinking nice things about him to disappear. As such, everyone in Peaksville, Ohio, including his parents Bill and Agnes, lives in mortal fear of him. The Twilight Zone (2002) sequel "It's Still a Good Life" features Anthony's daughter Audrey, who is able to bring back everything her father "sent away".
The Twilight Zone (1985): In "The Burning Man", Doug and Aunt Neva pick up a strange boy in a white suit while driving through Kansas. They soon discover that he is the genetic evil whom their earlier passenger, a seemingly crazed, disheveled man, warned them about. It is implied that the boy kills them.
An episode of Return of Ultraman dealt with a malevolent alien named Zelan in the disguise of a mute little boy visiting MAT headquarters. While the rest of the team thinks he's cute, the kid shows his true colours as he communicates with Goh telepathically, complete with some of the most nightmare-inducing sequences in the series as he psychologically torments Goh and gets away with it.
Vakishim from Ultraman Ace takes on the form of a little boy to hide from TAC during the episode, but also uses the form to go on a murdering spree, killing the kid's family and razing his village to the ground.
Flying Saucer Creature Blizzard from Ultraman Leo takes on the form of a mute little girl carrying a Creepy Doll. In this form, the monster wanders about town searching for scientists researching the Flying Saucer Creatures, and murders them with blasts of icy mist from the doll's mouth.
In The Walking Dead, Carl is turning into one of these. Justified, because he is growing up during a Zombie Apocalypse. First, he is forced to shoot his mother in the head after she dies, to prevent her from turning into a walker. Then he kills a child soldier from Woodbury in cold blood during the ambush on the prison.
Lizzie. She feeds rats to the walkers because she thinks of walkers as pets, then she eventually progresses to killing her sister and threatening to kill Judith as well.
Shane Botwin in Weeds is an interesting case — viewers get to observe the evolution of a Creepy Child, from "slightly affected by seeing his father die" to "13-year-old violent drug dealer and murderer", over the course of five seasons. It's anyone's guess where he'll go in season six...
The X-Files had a bunch of creepy children, all very disturbing.
Among the most iconic are Eves 9 and 10 in "Eve". They are look-alike cloned girls with super strength, super intelligence and murderous tendencies.
Michelle (Andrea Libman) from "Born Again" was reincarnation of a murdered cop and she was channelling his desire for revenge. Even her mother was scared of her. During therapy sessions, she kept disfiguring dolls in exactly the same way, always gauging out one eye and cutting one arm. This was how Charlie Morris's body had been mutilated to make it look like a signature execution.
In "The Calusari", we have troubled Charlie who is very un-child-like. Much more evil Michael who is his deceased twin. His presence killed his baby brother, father and grandmother... And he was about to murder a few more people, including Scully. His actor was pretty impressive.
Polly, a girl with a Creepy Doll in "Chinga" (an episode written by Stephen King). She's an autistic girl, but the creepiness comes mainly from the doll.
The army of small identical children, dark-haired girls and blond boys, in "Herrenvolk" have no language and just keep staring blankly at people. They were created to work as drones in a secret government project with genetically changed corn and bees. To creep and psyche Agent Mulder out even more, the girl drones look exactly like his little sister Samantha who was abducted as a child. The situation implies that her DNA was used in said project.
Gibson Praise who appeared in some Myth Arc episodes (e.g. "The End", "The Beginning", "Within", "Without", "The Truth"). He can read people's minds and at his first appearance, he avoided death by ducking. The man who died was shot right in front of him, but does he show the slightest bit of worry or fear, not just that someone was killed right in front of him, but that he was the intended target? Nuh-uh. He is also completely devoid of emotion at all other times and has no issue with pointing out how cruel and heartless people are.
Billy Underwood in "Invocation".
William could qualify as creepy too, if he wasn't intimately connected with Mulder and Scully. After all, he is/was genetically alien and had a habit of moving things with his mind. But he's just so darn cute.
Tommy Conlon from "Scary Monsters", who appears to be harassed by monsters, but it turns out that he was the cause of all the strange occurrences by conjuring them up in his imagination, causing several people to kill themselves.