Femme Fatale in training, a Fille Fatale (French for "fatal girl", idiomatically "girl to die for") is an adolescent or younger girl who knows how to use her looks to get what she wants.
While some will focus solely on their peers, others want actual grown men and will proceed to seduce one. She may well initiate a Teacher/Student Romance plot. This, of course, has much bigger implications for their victim — who is very liable to a sacking at best (if they're a teacher), with a statutory rape charge being more common (depends on jurisdiction, though).
Note that, in real life, children who exhibit sexualized behavior have often been the victims of sexual abuse. This is rarely addressed in fiction. In some people's opinion, overexposure to adult content like movies, porn, the internet, and music can cause the same kind of prematurely sexualized behavior, though how true this is is HOTLY debated.
Compare her Spear Counterpart, the Kid Anova. See also Jail Bait. In gay media, a particularly young and aggressive Twink can fill much the same role.
For obvious reasons, Dawson Casting is very likely. See also Troubling Unchildlike Behavior. In some Western countries (though certainly not all of them), a major source of Squick.
The above picture shows both Ren and Maria from Skip Beat!, the latter invoking this trope in a daydream in which she imagines the former professing undying love. Outside said daydreams, he's fond of her (not in that way) and pities her for her family situation, so he pays attention to her.
Older Than They Think: this archetype appeared in 1975 with Meg, the tomboyish heroine of the Magical Girl series Majokko Meg Chan. The girl is pretty aware of her good looks, is coquettish and outspoken (unlike the more mellow heroines of the time), and the OP of the series has her singing about using her beauty to woo guys and get what she wants from them.
Ibuki Yagami from Maison Ikkoku, who aggressively pursues Godai, her substitute teacher.
Neon Genesis Evangelion's Asuka Langley Soryuu has a blatant, possessive crush on Kaji (and raging 14-year-old narcissism in general) that turns out to be a symptom of her trauma and desperate need for attention to give her self-worth. Kaji doesn't accept her advances whatsoever, thinking she is much too young. She also makes a few subtle (and a few not so subtle) advances at main character Shinji Ikari, most of which pass over Shinji's head. In Rebuild of Evangelion, Asuka's crush on Kaji is completely absent, and she tries to win Shinji over by being a good cook.
Katja from Seikon No Qwaser, although she focuses on older girls for practical reasons.
Evangeline McDowell from Mahou Sensei Negima! seems like this at first glance, but the little detail about her being literally the secondoldest entity on campus (including the ancient principal, the ghost that has been haunting her current classroom for sixty years, and, in all likelyhood, the dragon under the library) sort of disqualifies her. Now, if only she would quit making passes at her (ten-year-old) teacher....
In Gunsmith Cats, Minnie May was working as a prostitute and taking age-slowing drugs to appeal to those with a young girl fetish.
Though it's explained rather vaguely, she used drugs in order to hasten her puberty so that her adult boyfriend wouldn't feel weird about being with her. She got breasts and hips a lot earlier than normal, but, as a side-effect, stopped growing for good.
Subverted in Soul Eater, where Rachel Boyd acts this way...but only when she's the victim of Medusa's Grand Theft Me. Once Medusa leaves her body, it's presumed she returns to be a more or less normal five-year-old girl.
Alois Trancy from the second season of Black Butler is one of the very few male examples; wearing skimpy booty shorts, acting slutty, having no respect for any private space...in fact, he's a textbook example for the behaviour of young victims of sexual abuse. Sadly, he is one: he and other boys around his age were Sex Slaves for a rich nobleman. Alois (or better said, Jim), already unstable from the death of his younger brother Luca, ultimately crossed the Despair Event Horizon and make a Deal with the Devil, summoning Claude Faustus...
15-year-old Flay Allster from Gundam SEED. When her father is killed by a ZAFT pilot, she decides that she wants the Coordinators of ZAFT dead, and also wants her former classmate Kira to suffer for failing to protect her father. Knowing that Kira hates killing but is also the only one with the skills to really combat the Coordinators, she feigns a romantic interest in him and manipulates him into fighting, including at least one instance of having sex with him. Eventually, her feigned feelings begin to become genuine, but she dies before she ever gets to make amends for her original motivations, leaving Kira believing she was really in love with him from the get go.
Given her age of only 13 years old, Kuroko Shirai's sexual fixation of her "Onee-sama" makes her this. Especially when you see her taste in underwear and swimsuits.
Jeremy from A Cruel God Reigns is a rare real life example in that in the manga, the entire first six volumes are a flashback to the sexual and physical abuse that he received at the hands of his stepfather. While this is going on, Jeremy begins to envision drinking Ian's blood in a fetish sort of way, and repeatedly forcibly kisses his roommate William (although this is more along the lines of Sex for Solace). In the latter, present day half of the story, Jeremy becomes a teenaged prostitute and is constantly making advances toward or is trying to seduce his stepbrother Ian to "bring him down to his level" and essentially punish him for not believing or helping him when he first confessed that he was being raped by their father. He seduces or trades sex for things like drugs from his older classmate Pansy or even a random adult at a party in exchange for a cigarette. Although on the older side at 16, Jeremy's flirtations are blatant examples of Fan Disservice and are far more adult than they should be.
Very cleverly and humorously applied in Calvin And Hobbes without it being the least bit Squicky. Six-year old Susie Derkins "charmed" stuffed tiger Hobbes into giving her his water balloon during a water fight, and she used it to drench Calvin.
Adrienne Forrester (Alicia Silverstone) in The Crush. A 14-year-old girl falls in love with her parents' house guest. When he declines her advances, she makes his life a living hell.
After a certain age, girls in any of the incarnations of St. Trinian's fit this trope to a tee.
Although it should be noted that St. Trinian's, like some of the other British examples listed on this page, features girls of 17 (the heavily sexualised Trinian's girls are Sixth Form students), and are therefore of legal age in Britain (Age of consent is 16 in the UK).
Kara from Brick, along with Laura Dannon. The two straddle the line between this and full-on Femme Fatale; they're high schoolers, but (seemingly) on the older end, and they're also involved in a variety of adult crimes such as drug dealing and blackmail. And one is indirectly involved in murder.
Tracy Flick (Reese Witherspoon) of the movie Election has had an affair with one of her teachers (who is now an ex-teacher).
Hayley Stark of Hard Candy appears to be an example at first — that is, until she throws it all aside, ties up the man she was previously seducing, accuses him of being a pedophile, pretends to castrate him, and generally just Mind Screws him until he commits suicide.
Angela in American Beauty, played by Mena Suvari, is one of these — except she never actually did anything; the tales of her sexual conquests of older men were fabrications, and Janey's father gently turned her down upon learning she was still a virgin.
Esther Coleman from Orphan. Or so we think, since her real name is Leena and she's truly in her 30's.
Iris in Taxi Driver, although she is probably forced into this situation
Regina's little sister in Mean Girls (who looks to be about nine) is seen imitating the girls on TV lifting their shirts up. Mark Waters says on the DVD Commentary that he felt it was the low point in his directing career asking the child actress to move closer to the teddy bear before flashing.
Bibi (Lynn-Holly Johnson) in For Your Eyes Only. James Bond even turns down the chance to sleep with her after she strips off and lies naked in his bed.
Mini, the Villain Protagonist of Mini's First Time, is, at eighteen, technically too old for this trope, but nevertheless is worth mentioning here since it is her youth that makes her seductiveness, manipulativeness, and evil so astonishing and compelling.
Sue Ann Stepanek (Tuesday Weld) from Pretty Poison would be a vamp if it wasn't because she was seventeen.
Nikki in Odd Girl Out, this aspect of her isn't directly relevant to why she's dangerous to the main protagonist, but we are told how she likes to manipulate boys.
Double subverted with Mia in Fish Tank. She is clearly intrigued by Connor from the beginning, but doesn't consciously act on it. However, when he starts reciprocating the interest, things turn inappropriate.
In John Steinbeck's "East of Eden", the character Cathy tricks boys into tying her up and fooling around with her at the age of ten, only to practice her ability to manipulate people. And this is only the first in a long life of shocking deeds...
In The Clique, Nina Callas is Alicia's beautiful cousin from Spain. She is able to attract most of the 7th grade boys, including the main characters' crushes. She also claims to have tons of experience with boys and knows what attracts them. It turns out that Nina was just using the boys to hide her kleptomania and was punished when she got back to Spain.
When we first meet 13-year old Mona Mayfair in Anne Rice's The Mayfair Witches trilogy, she has already seduced her way through a number of her male cousins and proceeds to seduce the thirty-something male protagonist. She later falls for a much older man, namely, a vampire.
Telling of Anne Rice's style that the only completely heterosexual character in her series' is seduced by a 13-year old.
Mona: I didn't lose my virginity. I obliterated all traces of its existence.
In Alatriste, Angélica de Alquézar uses this style to manipulate teenage squire Íñigo.
Adèle in Jane Eyre is a sort of G-rated nineteenth-century version of this, taking after her mother, who was an opera dancer, by being obsessed with looking good and proto-flirting.
In the Andrew Vachss Burke book Terminal, the murder victim, Melissa Turnbridge, is described as someone confident in and abusive of sexual power.
Felicity Worthington in the Gemma Doyle trilogy qualifies as a deconstruction, as she actually is a victim of sexual abuse at the hands of her pedophiliac father.
In Wise Blood, Hazel Motes briefly tries to seduce Sabbath Lily Hawks, the 15-year-old daughter of an itinerant preacher (mostly because Hazel wants to horrify the preacher). As it turns out, Sabbath is even more interested in seducing Hazel.
Diana Ladris from Gone starts the series at fourteen as a Manipulative Bitch with no qualms about using her appearance to get what she wants, which usually works. In the fourth book, when she's either fourteen or fifteen, she tries to convince Caine to follow her plans by sleeping with him. It doesn't work and has consequences. Somewhat justified, though, in that she's really not that young for the setting.
Sugar in the first season of Sugar Rush, when she is 15 years old. By the time of the second season, she is 17-18, so the trope no longer applies by that point.
Except for her showing up naked in Agent Dale Cooper's bed.
Several of the female characters from Skins verge on this, particularly Effy and Michelle.
Slightly scandalous in Effy's case, as the actress really was fourteennote Note that the age of consent in the UK is sixteen and having sex a year or two younger is exceedingly common. at the time of filming — no Dawson Casting there!
One of the major plot points of Californication is Hank sleeping with his ex-wife's soon-to-be daughter-in-law. She blackmails him for attention through the series.
One of the killer's victims in the Criminal Minds episode "52 Pickup" is depicted as one of these in a flashback sequence.
really "his", because it turned out the affliction of the episode was that she was genetically a boy, but had a condition which made him/her completely immune to testosterone
father because she knew that the threat of revealing that he had committed statutory rape with his own daughter would give her power.
In Copper child prostitute Annie. Although she has a major league Freudian Excuse, having been forced into marriage at the age of ten, to a man who treated her so badly that life in a brothel seemed preferable plus the pressures of survival on the streets of the Five Corners district of New York in the 1860s.
Lola Lombardi from Bully fits this one. She's pretty overtly sexual and uses it to con money, gifts, grades, and whatever else she wants from the male students.
Misha of Ar tonelico arguably starts as one, until she gains her adult form.
Illyasviel von Einzbern in Fate/stay night very much enjoys watching Shiro squirm when she puts the moves on him in the anime series. Also an Enfante Terrible and a Tykebomb. It turns out that she's actually biologically older than the person she tries to seduce, and only looks like a young child. And even after that, she doesn't have her own H-scene; in the Tiger Dôjô, we're told that she was going to have a H-scene in that gorgeous bed, but her route was dropped in favor of expanding the Heaven's Feel route.
Dahlia Hawthorne from Phoenix Wright: Ace Attorney: Trials and Tribulations seduced a childlike man at the age of 14 and forced him to make a suicide pact for her. It's her Moral Event Horizon moment. To make things worse, she has plenty more where that came from, and the Ephebophile she dated looks far more sympathetic than her as he kills himself in court.
Webcomic Better Days includes a girl who seduces the not-quite-old-enough main character and has sex with him repeatedly over the length of their relationship. Then, her abusive family is found out and she's sent off to foster care. The main character bears the psychic scars of his own abuse until he happens to meet her again...she's been through counseling and a loving foster family that taught her all the right things, and she's making a go at her own career, well aware now of the wrongs of her past (both those done to her and those she did to others).
Although she may look forward to find a guy she'll consider marrying, until then, she probably wants to enjoy her single life ass much ass possible.
Rose Crowley from Treading Ground (May be NSFW occasionally). It turns out that she is legal in her state by the time she starts chasing Nate Ashborne, but it is indicated that she lost her cherry long before then.
Paparazzi of the Whateley Universe, who is already a supervillainess while still in high school. Granted, it's Superhero School Whateley Academy, but still...
Solange (Tansy Walcutt) probably counts as well, since she's been using her feminine wiles and good looks to seduce and humiliate guys since she was fourteen.
Archer episode Swiss Miss, the underage rich guy's daughter ISIS is trying to protect. She tries to seduce Archer, and given his Anything That Moves reputation he has a hard time convincing his colleagues that Even He Has Standards. As the show spoofs spy movies, it may have been inspired by Bibi (Lynn-Holly Johnson) from For Your Eyes Only.