Children who are more mature than their age implies, with a solid comprehension of abstract concepts, good foresight and an understanding of human nature beyond what most kids their age have.
There are many ways to show that children are wise beyond their years: Kids who found themselves the head of a family and take their responsibilities seriously, the Kid Hero who actually treats his duty in a way an older hero does and doesn't simply see it it as an adventure, the teenager who refuses a stupid prank under all pressure, the cunning Enfant Terrible capable of planning and backstabbing that would make an Evil Overlord proud...
There may be a reason why these kids are what they are. Parental Abandonment (or even worse, a Teenage Wasteland) could force a kid to mature very fast, and a traumatic enough life could burn the childhood out of the most extreme and tragic examples of this trope. However, some of these characters are simply like this by nature.
This trope applies to a good portion of anime characters, probably to appeal to a young audience while still being able to let the characters exhibit more mature behavior, like engaging in fierce combat or taking up leadership roles. This consequently makes such characters more relatable to a mature audience as well, as long as it's done well and the matter of young age doesn't raise too many eyebrows.
Note that this is based on the mentality of the character. Just being shoved into an adult role won't cut it; the average Kid Hero and Bratty Half-Pint tend to be highly immature, after all. Intelligence tends to be different from maturity as well, some Kid Geniuses can invent hyperdrives in their backyard but act in a very childish manner everywhere else. A good number of kids under Improbable Age count, but if the kid is in a high-ranking position and still thinks like a kid, they won't fit here.
Frequently speak in Little Professor Dialog.
Contrast One of the Kids, Man Child, and Kiddie Kid. Compare Adorably Precocious Child, who tries to be like this but is still a kid at heart. Compare Child Prodigy, who is basically a TV Genius in child form. Innocent Prodigy is when a child really is like this, but still retains a childlike innocence in other aspects of life. Little Miss Snarker is a sub-trope of this, and when this character's maturity is displayed in a villainous light, he may become a Creepy Child. When every kid in a franchise acts like this (or at least most of them), it's probably because Most Writers Are Adults. Kids may be forced into this by living in a Teenage Wasteland. If the adultlike behavior is disturbing rather than impressive, it's Troubling Unchildlike Behaviour. If a Child Prodigy acts like an adult in a child's world, rather than being thrust into the adult one, he's Acting Your Intellectual Age.
Yes, despite his childish love of candy & games, his favorite pastimes are poker, chess, billiards, & shooting people in the face. Soma on the other hand is just a year away from becoming a Manchild.
Shiro Kabuto from Mazinger Z and Great Mazinger seems pretty mature for his age (specially compared with Kouji), and actually he is smarter than he looks. This is because Shiro is a full-fledged Iron Woobie is forced to life on his own withou a parents' care. His parents were dead, it is implied his grandfather Juzo spent most of his time building Mazinger-Z, and Kouji is busy handling the household jobs and going to school, thus leaving him alone. And let's not forget his supposedly dead father was too busy building Great Mazinger to take care of them AND tell them he was alive.
The human cast of Digimon Tamers exhibited a maturity way beyond their 10 to 11 years, one of several possible reasons their ages were raised in the English adaptations.
Every season of Digimon has one of these... even Digimon Frontier's Bokomon, who is the level named "child" in Japanese and who speaks and acts like a graduate student specializing in Digital World Mythology.
Henry/Jian of "Tamers" takes the cake though. I mean as is stated above he's 10-11 in the Japanese version...the kid can hack almost any computer system if you give him a good reason, and uses the word incorrigible in a relatively casual conversation.
At least the three previous computer masters had excuses like turning your computer into an attachment figure (Izzy/Koushiro), being said person with computer as attachment figure's semi-protegee (Yolei/Miyako) and having dark powers boost your intelligence (Ken). Henry/Jian has NO excuse at all.
Mikey, Nene, and Christopher from Digimon Xros Wars act more mature than most adults, and they're only 13.
Sora and Joe are the most mature of the original cast of Digimon Adventure, and as such take up the roles of Team Mom and Team Dad respectively while Tai and Matt fight over leadership, thinking of responsible things like how they will get food, what best course of action to take, and how to keep the group together. Tai later matures up later in the season as well.
The first time we see the 9-year-old heroine of Magical Girl Lyrical Nanoha, she's pondering the direction and purpose of her life. Later, when she discovers her powers, she almost immediately takes a responsible view of them akin to Spider-Man, except her wakeup call was property damage rather than the death of a loved one. Her parents also don't seem to mind their daughter taking time off from school to chase after magical artifacts.
The series also introduces us to Hayate. A wheelchair-bound 9-year-old who takes care of the Wolkenritter as their mother figure. Even before then, she had been living independently for who knows how long after her parents died. You'd expect that her guardian would at least have an adult look after her, especially considering her disability. In any event, it's highly unlikely that any social service would let this one slide.
Interestingly enough, Hayate, looking back on her childhood in Sound Stage M4, laments that she feels as though she hasn't grown up since then. Signum then responds that she has grown up at a reasonable pace, and that by comparison, Fate grew up too quickly.
Several other characters are like this as well, especially the calm and mature (if originally single-minded) Dark Magical Girl Fate, Adventurer Archaeologist Yuuno and interdimensional cop Chrono (who actually starts off under the command of his own mother in a sort of pseudo-subversion). One can assume that either Midchilda does not have the same cultural or legal expectations about Age of Majority that most Earth cultures do, or very clear laws allowing exceptions.
To Love-Ru has Mikan, the main character's little sister, as one of the most mature characters in the cast. Except for not hitting puberty yet, of course.
Doremi's sister Pop in Ojamajo Doremi, so much that her parents let her go on a train trip by herself. She's five years old at the time. Although it's clear at least that their mom Haruka was worried, as she asked Doremi to keep an eye on her after Pop had gone.
Every single member of the Arcobaleno in Katekyo Hitman Reborn! qualifies. Reborn himself could be a serious contender for poster boy of the trope, even before we knew the other six.
Johan Liebert became a Magnificent Bastard at ten years old when he made a building worth of people slaughter each other for his amusement, using nothing but force of personality.
While 10-year-old Negi of Mahou Sensei Negima! still very much enjoys being a kid, he has dedicated months of time to brutal Training from Hell, shown a deep understanding of both his friends and enemies, and has a powerful drive to find his father, such that he is willing to make great personal sacrifices. This on top of being a high school teacher of a Wacky Homeroom.
This gets covered in lampshades during second half of the Mahora festival arc, where just about everybody states that Negi is too young to be thinking about the moral implications of protecting the The Masquerade. Later on, he gets all sorts of speeches about how he should just act like a normal kid and stop worrying about everything. None of them penetrates his thick skull.
Negi is a Deconstruction of this trope as he literally has no idea how to be a child. Once when he was on vacation and was suposed to just have fun he tried approaching it the same way he does everything else: by carefully analyzing the situation and coming up with most efficient solution, until Asuna told him he should just relax for once.
There's also Yue. Fourteen-year-old high school student versed in philosophy and Negi's sounding board for moral dilemmas.
Chisame also qualifies, as she arguably has the best grip on reality out of everyone, and Jack Rakan even identifies her as being the advisor that Negi benefits most from.
Satsuki Yotsuba is head cook of a Chao Bao Zi. At the age of 14 she has her future planed and is actively working to achive it. Even Evangeline respect her.
It's hard to remember how young the children and teenagers are in this manga. Ichigo, Sado, Orihime and Uryuu start off as fifteen year olds, but are far more mature than their age wound indicate. Some of their classmates are the same, such as Tatsuki. Their Shinigami peers are the same: Renji, Rukia, Kira, Hinamori, Ganju, etc., are all teens but behave like adults.
Hitsugaya is (biologically) only 12-13 years old but doesn't behave like a typical child his age due to having been thrust into the role of youngest captain in history. Aizen works out that the truth is obscured and that Hitsugaya does actually have the in-built weaknesses associated with his biological youth (such as lacking both the life experience and emotional maturity of a grown adult). When Aizen triggers this weakness, the ignition of Hitsugaya's emotions into an Unstoppable Rage (and the other captains' inability to have foreseen this weakness) spells disaster for everyone.
Murasaki in Kure-nai yo-yos between believably childish behavior for her age of 7 and extremely adult-like decision making, especially near the ending of the series.
Kaguya Sumeragi in Code Geass, a fourteen-year-old girl with Puppy-Dog Eyes and a Precocious Crush on Zero, who often turns out to be one of the wisest, reasonable characters on the show and the one person Zero treats with complete respect while callously ordering around the rest of the Black Knights.
Nunnally seems to be in her way to become one of these in R2.
Don't forget; Lelouch is only 17 when the series begins. Older than most of the examples on this page, but still a little young for the kind of crazy stuffhe pulls off.
On top of that, he was already a Chessmaster in his early Britannia days.
Tomoyo from Cardcaptor Sakura is not only Genre Savvy, but is able to see the hidden intentions of every character she comes across even though she's a fourth-grader.
Even Eriol acknowledges Tomoyo's savviness.
Five year old Hatoko from Angelic Layer dispenses wisdom like Yoda but without the fractured syntax.
CLAMP School has the six year old kindergarten class president, and an adolescent Man Of Twenty Faces who steals large statues from under the noses of the police etc, and more.
Rihoko in the Witchblade anime, to the point of being smarter than her mother.
Shikamaru from Naruto, though you may pass him off as just a Teen Genius but he also already has plans for the future including his marriage, how many kids he wants and when he'll die. Not to mention he was willing to have both himself and his best friends go up against a much stronger opponent that would most likely kill them as to further the mission. This is all when he's 12/13. As Child Soldiers most of the cast would qualify but Shikamaru is the best example.
Itachi and Kakashi's backgrounds cast them as even more extreme cases: Itachi graduated the academy top of the class at 7 (all of the main cast did that at 12), passed the chuunin exams at 10, and became an ANBU captain at 13. He joined Akatsuki at 14 or 15. Kakashi graduated at five, passed the chuunin exam one year later, and became a jonin under special condition at 13.
Another good example is Sasuke, who was designed specifically to be in this trope as a contrast to Naruto. The author even revealed that he had trouble drawing him at first because he had a lack of experience in drawing characters who are "wise beyond their years".
A far more convincing example would be Gaara post-Heel-Face Turn: after years of serving as Sunagakure's Fifth Kazekage, he has not only become far more intuitive and rational compared to his hot-headed equals from other villages, he is also far more compassionate even to a now-Ax-Crazy Sasuke and a troubled Naruto.
Gaara: Peace under an illusion is not true peace. Peace is only meaningful when the world manages to accomplish it.
Hinata is the only one who sees Naruto for who he truly is waaaaaaaaaay before any of the other characters do. She offers him assurance and gives him back his confidence as Naruto fights Neji. Before that, though, she sees and understands Neji for the troubled and suffering soul he really is, which really set him off.
Almost all the child characters count to varying degrees, at least when compared to real kids their age. Justified that they live in a society where kids are given huge responsibilities from an early age, even being able to become ninja.
Alphonse Elric from Fullmetal Alchemist. While his older brother, Edward, wins critical acclaim time and time again for accomplishments thought ridiculous, Al consistently proves that he is rational, fair-minded and far-sighted far beyond his years. In fact, he often has to reign in Edward to prevent excess damage and often has to clean up if he's not able to prevent such excesses.
Edward himself proves to also be very wise and have a great understanding of the world, which in the end allowed him to recover his brother Alphonse by sacrificing his alchemy.
Also the series put much emphasis in the growth and maturing of the Elric brothers and the characters in general.
When we finally meet Ed and Al's alchemy master Izumi Curtis she comments how wise Edward must be to be able to perform alchemy without a circle however Ed responds that he isn't wise or clever; he just learned things he shouldn't have done by opening the gates of truth
In most cases Ling Yao is a perfectly good example of this serving. He keeps a cool head and is slow to anger and he notices things that others don't.
Seto Kaiba from Yu-Gi-Oh! He pretty much threw his childhood in the dumpster when he promised to always take care of and protect Mokuba. The fact that he rarely smiles and is exceedingly serious, not to mention he runs his own company, despite being only perhaps in his late teens/early twenties is actually commented on by several of the characters, notably Joey, Tristan, and Tea. Plus, the guy beat a chess grandmaster at age twelve, and then proceeded to turn ten thousand dollars into about ten million dollars in the course of one day, when he had a year to do it.
Tessa from Full Metal Panic!! is only 16, yet she is the captain of a submarine. She also shows a great understanding of people and exhibits a very mature attitude. She's also damn good at her job. However, she is not completely immune from some general characteristics of teens.
Sōsuke is 16-17, and is a sergeant within a paramilitary counter-terrorist force. Although extremely immature for his age about relationships and social skills, he is shown to act very professional and understanding about things involving war. He was trained to be a professional assassin at age 8, and became a terrorist at 11.
Asuka from Evangelion is a 14-year-old Teen Genius and something of a special case. On one level she understands just how suicidely dangerous being a pilot is, and has made peace with it (at least at first). She also shows impressive understanding of other people's motivations and relations (with the notable exception of Rei — she's aware of Misato/Kaji, just in denial). On the flip side, she is very short-tempered and more than a bit spoiled. Basically she alternates between acting twice her age and half it.
There's also Rei, who is cited by another character as seeming "far older" than the rest of them. Finding out at a young age that you're a half-clone of the mother-god of all humanity might be expected to age you pretty quickly, after all. Not to mention the whole "reared for piloting, infinitely replaceable, no time for childhood" thing.
13-14-year-old Victorique de Blois from Gosick, though she admittedly has traits common for a child of her age, such as curiosity and a love for sweets.
All the girls in Gun Slinger Girl are aware that they are on borrowed time, and that their feelings for their handlers are at least partially the result of conditioning. Triela and Claes are the only two to have made their peace with the fact they will never see adulthood. Though they deal with the knowledge is opposite ways (despite being roommates).
Both Kyon and Koizumi of Suzumiya Haruhi fit. Kyon is a little too much of a jaded cynic for just being 16 years old.
17-year-old Maria from Hayate the Combat Butler already has a full-time job as a maid, and is also mistaken for being in her late twenties or early thirties because of her maturity level.
Maria is continually pointed out to be not mature, but intelligent.
Hayate himself, almost certainly... he's a full sixteen now, but has already evaded the yakuza, served under Athena (who is supposed to be of similar age), and is already a prize-winning manga artist... seriously, with the luck factors so hard down his throat, he really had to be to make it past the age of 8...
Hayate clearly states that he supported his parents starting at 10. His bad luck is more of an informed ability than anything given that he is the main male in a harem story.
Though one could argue that that is bad luck considering the amount of physical and mental abuse he suffers because of it. Especially bad luck considering he is surrounded by a harem and yet is forced to be a Chaste Hero until he has enough money to support even one of the girls, which, given his 150 million yen debt, is highly unlikely.
Hinagiku also has a similar level of maturity, most of the major cast in on the low end of this trope as well, showing maturity beyond what someone would expect from a 16/13 year-old. Even Yukiji seems to have it, when it's not overshadowed by her Hard-Drinking Party Girl tendencies.
Several of the Bokurano kids like Kirie, Moji and Kodama. But 10-year-old Kana takes it to borderline ridiculous levels. Accepting a constant abuse of her older brother Jun and preventing people around them from interfere, because she knows he's angry at their dead mother for her absence, and by taking it out to her he's in reality treating her as somewhat of the mother figure? Not even being Jun's blood-sister, but hiding it from him in order to make him feel secure, she devotes herself to finding his real mother. In the manga, while she's about to die it remains her biggest concern - because Jun's gonna need support after she's gone.
Fuji-hime from Harukanaru Toki no Naka de might fit this trope, since she is effectively the team's mentor — even if most of her knowledge comes from her ability to see the future, she is arguably more mature than some of the members of the central cast (whose age ranges from 14 to 32, with Fuji being only ten). Might have something to do with her destiny to assist the main character, but still...
Chiru from Xabungle is all of 8 but consistently manages to be one of the more level-headed characters in a cast of teens and adults. This is significant, since in 1981 children in anime, if they weren't the main character or in a cast of mostly kids, were typically The Load or a Bratty Half-Pint.
Wendy Garret of GUN×SWORD, who's maybe 13-14, is in many ways more mature than her traveling companion, Van. More importantly, she functions as the moral center for the series, being one of the few characters to think deeply about the moral/ethical issues surrounding The Claw's plan.
Most of FLCL revolves around how Naota rejects his childhood.
Akemi Homura from Puella Magi Madoka Magica is a darker take of this trope (like everything else in the anime). She only knows better than everyone else because she was forced to repeat things again and again and again, each iteration worse than the last. Having a goddamn alien conspiracy as her Arch-Enemy doesn't help.
In the flashback arc of Trigun we get young Knives. Levelheaded, charming, genius programmer—one year old. He's also got a fair helping of cynicism and subscribes increasingly to a utilitarian philosophy, which eventually propels him into deciding to Kill All Humans. But hey. He was unreasonably wise all the same.
Their response to the Tesla revelation is electing to sit down right there and stay there until they die, rather than running to their mother figure and if not asking her for comfort at least confronting her about her betrayal. Tell me that's not unchildlike.
Manga Wolfwood was shot for the first time when he was eight or so, and suddenly realized that he wanted to live, after all. Anime Wolfwood was abused and offed the bastard at a slightly older age.
Manga Wolfwood was subjected to medical treatments that aged him at an accelerated rate, and based on the ages of the other kids in the orphanage in the flashback and when he returns, he can't be older than eighteen when he dies, which makes him no more than sixteen when he met Vash. So he's kind of this for the entire series.
Little Legato is somewhere between eight and thirteen, probably on the younger side, but his response to Knives appearing and killing everyone but him, including the building they were raping him inside, is...uniquely calm, to say the least.
And possibly Zazie the Beast, anime version. Or he may be an adult with a hormone condition. Data insufficient.
Every kid on this list except Vash is also under Creepy Child.
Sasami of Tenchi Muyo! is this, especially after the first OVA series. Cooks and cleans for the household, the more levelheaded of the bunch, sweet and adorable and closest thing to an adult in the house is Katsuhito, who lives in the shrine instead of in the house. On the other hand, a lot of this may be a cover because she thinks she's actually just a vessel for Tsunami and that the real Sasami's dead. Which isn't the case.
Elaine Belloc from Lucifer, particularly after she returns from the dead and loses both her naivete and crush on the title character. (The readers subsequently learn that even before her death a teacher described her as "twelve going on forty."
Zodon from PS238, due to his four-digit IQ, has the mental age of a very cynical thirty-year-old in a seven-year-old body and most of his actions tend to fly over the heads of his classmates as a result. Another offender would be Victor Vonfogg, who is just about as smart (but more prone to stereotypical Evil Genius behavior).
Tom Davidson, the time- and space-traveler, is another example of this trope as his abilities allows him to see things other people can't (and never will). His description as having a "Gandalf the Grey vibe" pretty much fits like a glove.
Tyler Marlocke also falls under this trope, as a normal kid whose being forced to go through a curriculum designed for people with superpowers by his parents, he often has to rely on his innately sensible nature in order to simply survive. After he becomes the de-facto main character, he is able to solve many problems simply through a heaping helping of good, old-fashioned common sense and some rather advanced deductive abilities. It helps that later on he gets occasional supplementary lessons from local Badass Normal and Batman expy, Revenant.
Huey, Dewey and Louie, the nephews of Donald Duck, frequently come across this way in the stories of Carl Barks. Of course, next to ill-tempered, irresponsible, immature "Unca Donald" and even greedy, miserly, tunnel-visioned Uncle Scrooge, it doesn't take much to be the most responsible ones in the room, especially when aided by a Hive Mind and a Great Big Book of Everything.
Layla Miller from X-Factor. She knows stuff. It was eventually revealed that she's like that because her future self loaded her memories into the brain of her present self.
Damian Wayne from Batman, son of Bruce and Talia al-Ghul, starts out as your average Bratty Half-Pint. Slowly, beginning in 'Batman and Robin, under the constant tutelage of Dick Grayson and after being imparted a couple of lessons in teamwork from Tim Drake, sheds his brash cockiness evolving into an overtly serious, competent but gloomy hero. Basically, a little clone of his daddy. Stephanie Brown, the third Batgirl (not counting Helena Bertinelli) comes actually to pity his utter inability to act his age anymore, being a 10 yrs old kid unable to play or interact with other toddlers, but deadly competent in crimefighting and investigation, with snarker-tendencies.
Bruce Wayne himself, in several renditions of the mythos, is known to have never smiled again after the unfortunate death of his parents, shedding away his childhood at once to hasten his growth into the deadly crime-fighter we know currently. Lampshaded in the animated retelling of the mythos, Justice League Unlimited, where, after temporarily being turned into children by a magical spell, Wonder Woman merrily quips how it was kind of nice to be a kid again. Batman simply shrugs, and shatters her joyful spirit by muttering "I haven't been a kid since I was eight years old."
The eponymous character of Ferris Buellers Day Off. Conventional wisdom would tell us that he should be studying, preparing for his future, but he knows that the future is now; it's today. He's not going to spend his whole life wishing he had done something, he just does it. He also helps give his friend the confidence to move beyond his Parental Issues and take control of his own life, all while thwarting the attempts of Dean Bitterman to bring him down and imprison him in yet another year of high school.
The kid La Résistance team Wolverines in Red Dawn (1984) fancy themselves as such, but still make rash and heat-of-the-moment-driven decisions.
Men with Brooms: After Amy falls Off The Wagon, Chris Cutter attempts to tell her son that she's sick. He replies that even he can tell that "she's shitfaced." He promises to look after her for the night just the same because "She's the only mom I've got."
In Quest Of The Delta Knights, T is portrayed this way. An example, when he and Leonardo de Vinci find themselves captured with no means of escape, Leonardo frets about what they're going to do and how T can try to sleep at a time like this until T tells him, "when in doubt, rest." Crow responds, "You are full of crap beyond your years, kid."
Matilda: Matilda can multiply large numbers in her head (13 times 379, for example) in seconds, and says she likes to read just about anything. It's strongly implied that the only reason she isn't in an enrichment or advanced placement program by now is because her parents don't believe in the value of education, as implied by their reaction to her teacher's point that with private instruction she could get to college years early.
Mrs. Wormwood: You want Matilda to go to college?
Mr. Wormwood: College? I didn't go to college. I don't know anybody who did. Bunch of hippies and cesspool salesmen, ha ha ha ha...
Mattie Ross, at least in the 2010 adaptation of True Grit. Her determination and drive to catch her father's killer gives even the most hardened bounty hunters pause, coupled as it is with a genuine seriousness and an impressive knowledge of law and scripture. Deconstructed, however, in that she is still naive enough to be vulnerable, and her lack of innocence as a child leads to an apparently joyless and lonely adulthood.
Aside from being physically the youngest Avenger (early twenties), Captain America in The Avengers has the experience of a soldier and it allows him to see the best way to handle just about any battlefield. It makes him the greatest and most competent field leader to serve under, age be damned.
The Baudelaires, most notably Sunny, who's a baby for most of the series!
Also, most members of the VFD.
Matilda: Matilda can multiply large numbers in her head (13 times 379, for example) in seconds, and says she likes to read just about anything. It's strongly implied that the only reason she isn't in an enrichment or advanced placement program by now is because her parents don't believe in the value of education.
The Dresden Files: The Archive is the ultimate example of this trope. She is a seven-year-old girl who possesses the sum total of all human knowledge. Everything that had ever been written, or in the case of information on computers, printed out (she doesn't "learn" it until it is printed) she knows.
In the Chung Kuo series, several of the characters are first introduced as children in the first novel
Ender of Ender’s Game, who is more mature than just about any other 6-year-old ever. By contrast, Bean is even smarter than he is, but as amoral as you'd expect from a street kid.
Charles Wallace Murry, of all Time Quartet books in which he appears, but most pointedly in A Wrinkle in Time, when he's about six years old and is well aware that he's twice as mature as his nine-year old brothers and his fourteen year old sister. However, this does turn into his downfall.
Luna Lovegood of Harry Potter, who combines this gracefully with Cloudcuckoolander. (Her mother died when Luna was nine, and her father doesn't seem to grasp all of his responsibilities perfectly...)
Then there is Harry Potter himself, who, at age 11, realized that being cursed forever was a Fate Worse than Death.
Oonagh from Prophecy Of The Stones, who at first seems to be a sweet, playful, innocent, barefoot girl, but in reality is a wise sorceress and the oracle. However, when she is asked questions she doesn't want to answer, she switches back to her childlike state and happily sings prophecies to herself.
Goth, the heroine of The Witches of Karres by James H Schmitz, a 1967 space opera. Goth is the middle sister of a trio of witch children, members of a super-psychic race/culture of humans. Her super-psychic powers, though, don't account for her relative maturity. She's elevenish, but not only teaches the adult hero magic, but advises him on political and economic moves. The hero only gets limelight because (1) he's the viewpoint character and (2) for a considerable time, Goth is kept off stage or unconscious.
Pearl from The Scarlet Letter. This is exactly how she is thought of in-story (in fact it's part of the reason so many people think she's some kind of demon child).
The main cast of Animorphs, especially Jake. How old they are isn't made clear until the end of the series, but it turns out they were 13 at the beginning and 16 at the end.
With the crap they go through; they'd want to be.
Also, this is shown largely through Character Development. Tobias and Cassie start off "a bit mature for their age" — Tobias due to Foster Parental Abandonment, Cassie becuase she helps her dad run a wildlife shelter, and is used to life-and-death decisions and serious consequences. The others start as fairly normal, and it takes them a few books to stop goofing around. After a few months fighting an Alien Invasion that could be anyone, anywhere, though, they're wise beyond their years. If they weren't, they'd be dead by then.
Alia, Paul Atreides's younger sister in Dune, thanks to being in the womb when her mother connected with the Fremen Reverend Mother.
Paul himself was this in the first novel. He was only fifteen but spoke and acted like an adult, and usually treated as such because of it.
Eliot from Space Vulture is an excellent example. With no prior experience other than reading about it in books (and sometimes not even that, coming up with ideas on the spot), he hijacks a spaceship from the experienced interplanetary thief and all-around ne'er-do-wellGil Terry and promptly shows that he can operate it better than its owner. A little later, he defies all common sense as well as the laws of physics by steering a lifeboat into a planet's atmosphere from the outside. You don't resent him, though, because of his noble purpose, the fact that he makes a terrific foil for Gil, and because he's either utterly terrified or at least highly anxious most of the time, and not a smug smart kid at all.
Herald-trainees who take the 'usual' route to Herald (brought to Haven in their early teens) grow up fast. By the time they are full Heralds, around the age of eighteen, they are much older mentally and emotionally. Their bonds to their Companions and fellow Heralds usually hold off the unpleasant consequences of such rushed maturation.
Also, Talia's people consider their children adult as early as 13, and with the sort of upbringing she received, she's already something of a "miniature adult" when (at said 13) chosen for a Herald.
Taran, the young protagonist of the Chronicles of Prydain, begins the series as a witless child, who only cares about adventure and glory. But as Character Development takes effect over the course of the books, he eventually becomes so wise that he earns the respect of kings and war leaders decades his senior.
In Discworld, one of Susan's young charges is six, but according to Susan 'in cynicism, she's about thirty-five'. She writes letters to Death on pink paper with pictures of mice on it, so that he'll think she's cute.
And again in Good Omens, where Wensleydale is called 'Youngster' by his parents, in the hope he'll take the hint.
In a weird way, Adam.
Title character of "Teddy" from J.D. Salinger's Nine Stories, who outshines his adult interlocutor Bob Nicholson (and—one imagines—most of the shrinks and scientists for whom he's an object of study). Knows precisely when he'll die, which of course wouldn't be mentioned if it weren't relevant to the plot.
Dale Brown novels have Bradley James McLanahan, who shows surprising maturity about the topic of death in Wings of Fire.
In John Dalmas'd The Regiment, the main character visits Tyss, homeworld of the Private Military Contractors in the title, and finds their educational system produces children who fit here. A girl of about five approaches and asks if he and his colleague are "Ertwa." The child's brother, roughly seven, points out that "Ertwa were very long ago," and says the two must be "Splennwa" (from planet Splenn) instead.note They're actually from Iryala, but most offworlders who come to Tyss are Splennites. The -wa suffix in the language of Tyss indicates people from such-and-such planet, so "Ertwa" are from "Ert" (Earth?)
The little girl studied them. "Splennwa?" she said, cocking her head critically. "I think not. They are abroad unprotected in the heat of day."
In the Deryni works, this is apt to happen to Haldanes and Deryni children, especially with the pressures making them grow up fast.
Kelson's deft questioning of his father Brion in the first chapter of Deryni Rising. The prince is a couple weeks shy of fourteen, and Brion admires his son's shrewd intellect.
Perhaps the best example is the four-year-old Alaric Morgan in Childe Morgan. Alyce is conducting a Naming ritual (which is usually done when the child is seven or eight), and she questions him as part of the ritual:
"Alaric," she began, "I know that Father Anselm has talked to you about the difference between right and wrong."
Alaric nodded solemnly.
"Do you think you could tell me about something that's wrong? Can you give me an example?"
The boy cocked his head thoughtfully, then looked at her with all the wisdom of his four years.
"Do you mean just naughty, like when I kick Cousin Kevin, or really bad?"
Alyce had to concentrate to keep from smiling at the sagacity of that answer. She need not have worried about her son's understanding.
Septimus Heap in Septimus Heap is this thanks to his Young Army days to the point that he becomes ExtraOrdinary Apprentice at the age of 10.
Otto in Someone Else's War. While most of the child soldiers are there against their will, Otto joined the LRA willingly because he knew his impoverished parents were having a hard time feeding all four of their children. He did this when he was eight. (By the start of the story, he's twelve.) He is even smart enough to realize that, despicable as the war is, if he kills his enemies before the adults get their hands on them, he is saving them from a great deal of suffering.
Tortall Universe: Kel from "Protector of the Small" has a bit of this. Lampshaded by Neal, who says she's "The oldest ten year old I've ever met"
Also from Tamora Pierce, Circle of Magic, the Child King of Gyongxe, who was apparently selected to rule by the gods themselves, and incredibly mature for his youth. The main protagonists (Sandry, Tris, Daja and Briar) also count at times.
Aristok Kassandra the Sixth of Branion, aged five, is a God-Empress with fiery eyes that give her an "eerily adult" gaze. She is childish and talks with a lisp, but has the vocabulary and understanding of someone aged more like eight or nine. This appears to be justified by her divine status. As sovereign of her country, she has a regent but makes adult decisions and intimidates nobles, priests and even traitors into doing her bidding. The one thing they won't let her do is execute someone; she has to be sixteen for that.
Having learned to take care of her mother over the years and being naturally responsible, Bella had developed into a very mature person, especially for her age. She even starts out Twilight by telling the reader that she's prepared to die in the place of someone she loves. Once she's fallen in love with Edward and he leaves her in New Moon, this is subverted as Bella turns out to be immature, whiny and lacking in self-control, as first seen when she throws tantrums at her parents for trying to get her to move back with her mother.
The Baby-Sitters Club suffers from this accidentally, probably due to the Most Writers Are Adults trope. 13-year-olds are given responsibilities most adults in Real Life wouldn't entrust to a high school senior, such as taking little kids around New York City unsupervised. All the BBC has to do is offer to help and explain that they have an after-school baby-sitting business, whereupon one of the parents they'd worked for would chime in with, "They're very responsible," and bingo, they were treated like honorary adults, no further questions asked. And since eleven is apparently the magic gateway to the Competence Zone, often Mallory and Jessie would be "taking care of" kids who were only a year or two younger than they are.
Also, some of their sitting charges as well (when they're not acting a lot younger than they should be, such as five-year-old Andrew who doesn't know what New Year's is). Take for instance one of the Perkins girls: she's two years old, and yet speaks in complex full sentences and acts more like she's around TEN!
Alexa in The Fire Eternal. It's strongly implied that she chose her own parents and family before her birth, and has been manipulating things behind the scenes for a long time beforehand.
In the Rainbow Magic series, Rachel and Kirsty are this, contrasting heavily with Jack Frost's childishness.
The English Dragon: Several chapters are narrated by Ben, the toddler. His remarkably eloquent inner voice is lampshaded. Ben represents naivety and Everyman - a literary device to see everything but to do so in an objective/naive manner.
Live Action TV
Buffy the Vampire Slayer: Despite being the most innocent of the Scoobies, Tara takes the revelation of Joyce's death much more like an adult than any other member of the gang. We later learn it's because her own mother died when she was 17, so she's been through this before.
Ziva from NCIS mentions that as a child in Israel, one has to grow up quickly or else you get killed.
Several Power Rangers characters, including the original Mighty Morphin Rangers. Trini in particular stand out among the original six, but they all displayed a significantly higher degree of wisdom than you'd expect of highschool freshmen or, in fact, the average adult. Zordon chose well.
Veronica Mars has the titular character, a private eye who not only makes a number of references that should really be beyond her range, but also regularly outsmarts many adult characters over the course of the show despite being a teenager. There is also the matter of her emotional duress which has granted her a cynicism more typical of a divorced adult.
Huey Freeman in The Boondocks, moreso than the show below. Especially as time goes on and his character is fleshed out. To the point where his lawyer neighbor often comes to him for poignant, intellectual conversation instead to his political-activist wife.
Linus from Peanuts is often a good source of advice.
This is an usual portrayal of child Venerables, Blesseds and/or Saints in the Roman Catholic Church. Examples: Saint Maria Goretti (12), Saint Agnes of Rome (13), Saint Domenico Savio (15), Blesseds Francisco and Jacinta Marto (11 and 9, respectively), Venerable Antonietta "Nennolina" Meo (7), etc.
For that matter, just remember 12-year-old Jesus and his behavior in the Scriptures, when Mary and Joseph lost track of him. When found, he told her that she needn't have worried, and asked why they hadn't checked his father's house first. Mary and Joseph found Jesus discoursing with grown men on the scripture when they finally checked the temple after three days of searching.. He was exactly where He knew He had to be: in His Father's house. (Luke 2:49)
David (before he even became King) could be interpreted as this.
"I am young in years, and you are old; that is why I was fearful, not daring to tell you what I know ... But it is the spirit in a person, the breath of the Almighty, that gives them understanding. It is not only the old who are wise ... Therefore I say: Listen to me; I too will tell you what I know."
Sanaki from Fire Emblem: Path of Radiance and Radiant Dawn had been an empress since she was five, and still managed to avoid or even fight against the corruption of the Senators.
Roan from Grandia II is one of these. Being raised to rule a country partly explains it.
Blitz, in Balmung Cycle, especially relative to the people around him.
Ken Amada from Persona 3 is another, largely due to the fact that his mother was killed in an accident some years prior. Said "accident" is later revealed to have been caused by another Persona-user, thus prompting Ken to join SEES to seek his revenge.
Not to mention six-year-old Nanako from Persona 4 who pretty much takes care of herself, and does all the housework, and is the pride of her elementary school. She basically stepped into her mother's role after her death, and both her Social Link and her TV dungeon make it clear that she's never quite gotten over that.
Naoto is an older example, being an Ace Detective and called upon (if not respected) by the cops despite being a first-year high school student. Her Shadow flips between Little Professor Dialogue and childish crying, manifesting the divide between how she presents herself and how the world really treats her.
And of course, we have the titular princess. Whether as a child, a teenager or a young adult, she is far wiser than her age would imply. This trait is the very reason why she was granted the Triforce of Wisdom.
Mission Vao from Knights of the Old Republic could be seen as this, as she had to become very street-smart very quickly after her brother abandoned her on Taris.
In the .hack series, Wiseman. At the time of the original games, he's ten years old. You would never guess this from his efficient, calculating, highly intelligent on-line persona.
Sakaki in .hack//GU is a similar case: an elementary school student who is on the governing council of one of the largest Guilds in the game and is constantly giving speeches about morality to people much older than he is. He also tries to Take Over the World through AIDA in order to enforce his standards of morality on everyone.
Fallout 3's protagonist, the Lone Wanderer, is only 19 at the start of the game. Even so, fresh out of Vault 101, one of the first things you can find yourself doing is demonstrating that you are perfectly capable of disarming a nuclear bomb.
The Mass Effect series fits in a rather bizarre way; alien races have different lifespans, cultures, expectations, etc., but the series also reinforces that age alone does not determine wisdom. Thus, people like Thane (who can't be more than 50 years old) display maturity and wisdom on the level of Samara, who is somewhere near a thousand years old. This makes the moments where Shepard impresses/helps them in terms of wisdom and actions this Shepard is (barely) less than 30 years old for the first two games. Wrex, who is at least 1400 years old, also displays plenty of wisdom (uncharacteristic for krogan) and character development; the latter is actually thanks to Shepard.
Suikoden V gives the main character, the Prince of the Queendom of Falena, and his sister, the Crown Princess And eventual Queen. The Prince is between 16 and 18, and he's already a badass Warrior Prince with political savvy and commands the respect of his entire army. Lymsleia is all of 10, and she's a masterful politican who engineers a plan to escape house arrest that only fails due to a defection. They get it from their mother Arshtat and aunt Sialeeds, both political geniuses.
Ever17 has Yagami Coco. While she normally acts quiteenergetic, events later in the game (especially during Coco's own route) reveal that she is more aware of how serious the situation is than most of the rest of the cast, despite being the youngest.
Yuni from Remember11 also sporadically shows hints of this. He puts up an act so that the others don't realize this.
Maji De Watashi Ni Koi Shinasai has Monshiro, who has skipped grades, acts extremely mature and is considerate of others' feelings - arguably moreso than her brother Hideo, who seems to lack an "off" switch.
Rika from Higurashi no Naku Koro Ni at times exhibits a mental capacity far beyond that of a child. Of course, that makes sense when you find out that due to the "Groundhog Day" Loop she's been stuck in, and being the only one who retains her memories, mentally she is actually hundreds of years old.
In Ace Attorney, Franziska von Karma. She became a legal prosecutor at age thirteen, and went undefeated for FIVE YEARS.
In one of the rare cases where twelve-year-old Annie actually acts her age, she ends up collapsing in tears, crying that she misses her mother. One might assume that she wears her maturity so tightly, because the child can't handle that pain. (Or maybe it was just those cherries.)
Redcloak from The Order of the Stick. He was only an acolyte for the Dark One when he was forced to take on the Crimson Mantle — a religious artifact that literally freezes his body and mind in time, making him immune to maturing, aging, and disease. Anyone who reads only the strip on the Internet would guess that he was at least in his mid-twenties. At least. In reality, because of the mantle, he's somewhere between ten and fifteen years old. Of course, if you discount the mantle, he's been alive for about half a century, which is actually pretty old for a goblin.
Interestingly, in the Start of Darkness prequel, Redcloak's brother accused him of being an inversion, essentially saying that largely due to being frozen in time and without having to face his mortality or changes, Redcloak is still the same angry kid who watched his mentor and family be slaughtered. Redcloak has never moved on, now making him more like an example of the saying "there's no fool like an old fool".
Deena in The Guild seems much more mature than her older brother. Of course, considering that her brother is Bladezz that's not very difficult.
The Fool Fantastic, a member of That Guy with the Glasses, is one of the smarter members. He reviews the best movies of all time, attempting to figure out what makes them so great. You'd be suprised to learn he's 17 with all the classic films he reviews and references.
Suzie Carmichael in Rugrats told Angelica where babies really came from, but since her mom is a doctor, it shouldn't come as too much of a surprise. One of her older brothers, Edwin, is a much better example of this.
Lisa Simpson on The Simpsons, and this has quite often been a plot point of the show.
Aang himself counts later in the series, being only twelve but having the WIS score of 20. But then again, he is the Avatar. He is chronologically a hundred and twelve years old. He was frozen for a hundred years, so mentally he was still twelve at the beginning of the series. He matured a lot throughout the show, however. Same can be said for most of his friends, as they are all young and manage to fight armies on a daily basis, almost. A point is made of this in the episode The Southern Raiders. When Katara sets off to avenge her mother's death with Prince Zuko, Aang makes it a point to advise her several times. At the end, Sokka responds with the line: "You know, for a kid, you're pretty wise. Usually it's annoying, but right now I'm just impressed."
Speaking of which, Katara is probably the best example of this. From a very young age, she has had to act as a mother to her family and her brother, and her actions and reactions throughout the series reflect this very strongly. Though she occasionally has "childish" instances (half the time just to make a point), the series treats her as the group's mother figure and caretaker. Take this dialogue from the very first episode:
Katara: (while penguin sledding) I haven't done this since I was a kid!
The DCAU brings us Kai-ro, the ten-year-old Green Lantern from Tibet. A ten-year-old wielding a willpower-based weapon, who was easily the most level-headed member of his incarnation of the Justice League. Badass.
Jeremie Belpois of Code Lyoko is not just the leader of the Five-Man Band, but devises all the planning and strategies in the fight against XANA, sometimes even keeping ahead of the malevolent AI. Hence, even for a Teen Genius, he proves much more mature and serious that could be expected from any 11/12-year-old. At least, as long as Aelita isn't directly involved... then he can get emotional and show his true age.
The Monster Buster Club members are twelve years old. Said twelve-year-olds regularly beat up evil aliens and save the day with a combination of gadgetry, teamwork, and physical prowess bordering on Charles Atlas Superpower.
In South Park, all of the students with the exception of Butters have shown to be consistently more intelligent than the adults especially in the later episodes and understand many complex things.
The basis of the main plot of the episode "Cartman Joins NAMBLA" is Cartman feeling too mature for his friends and attempting to make friends with adults. It worked far too well.
This appeared to be the entire premise of FOX's animated series Allen Gregory. Unfortunately, the kid was also an unlikable twerp, so the show didn't last.
Members of Codename: Kids Next Door sometimes show signs of this trope, which can ironically imply that they can be more mature than some of the villians they face.
Especially Numbuhs 1 and 5. They've both been in life-threatening situations too many times to count, Numbuh 5's got the wisdom of somebody at least twice her age, and Numbuh 1 has a relationship with his girlfriend that some grown men would envy. They're both 10-11 years old.
The biggest example of this trope would probably be Numbuh 362, considering she's in charge of a whole global organization filled with thousands of kids.
In Nick's new Teenage Mutant Ninja Turtles, Leonardo is responsible for the lives of his three brothers, the protection of his home and sensei, and occasionally the fate of the city. He's fifteen years old (no older than the rest of his brothers).
Tommy Anybody from Mr. Bogus appears to show shades of this.
Spike, the iconic baby dragon of My Little Pony: Friendship Is Magic, is at least four years younger than the mane cast, but more often than not acts with their level of maturity and wisdom, if not even more. Except when he gets jealous or overeager to show results, that is, though such lapses of maturity aren't at all uncommon among adult ponies either.
Babur, the first Mughal emperor of a good chunk of India and the important bits of Afghanistan, became an independent ruler and military leader at 12, fighting adult enemies who more often than not had vastly more money and soldiers than he (including the freaking Khan of the Uzbeks). He made a career out of beating larger armies, and crowned it in his adult life by eating the Delhi Sultanate.
Many children can appear like this, not understanding social cues or tact and will speak bluntly and truthfully as they see it.