Many Big Bads feel the best minions are homegrown ones. Tykebombs are typically raised from birth (or creation, for Sci Fi) or early infancy with the idea of serving out of loyalty. This means putting an immense amount of potential power into the hands of a wildly inappropriate user, usually a young child.
These villains would probably be more effective if said creations were not typically abused or treated badly by villains who insist they exist to serve their master, rather than being coddled and praised. This usually culminates in The Dog Bites Back, followed by escaping and eventually becoming a thorn in some hero's side. If the character is an actual child, this can complicate the hero's sense of morality of how he deals with people. Expect all but the worst of Anti Heroes to try Defusing the Tyke Bomb.
Notably this trope is derived from real life, as many cultures took to training elite warriors from an early age. Medieval knights were commonly trained from early boyhood by a Knight mentor (the word boy is even derived from a word for "servant"). Middle Eastern mamluks and Turkish Janissaries were relatively similar, as are certain Asian warrior monks. The real life Spartan Way began at age 7, making the trope at least Older Than Feudalism.
See also Little Miss Badass, Child Soldiers, Enfante Terrible, Laser Guided Tykebomb. Can overlap with some types of Super Soldier, especially those brought up in The Spartan Way. For someone who's a literal bomb see Why Am I Ticking? or Action Bomb. May result in Sacrificed Basic Skill for Awesome Training, usually empathy. Not to be confused with Baby Boomers. Contrast Upbringing Makes the Hero. Weaponized Offspring may be a subtrope of this.
For kids who are raised to be scientists, musicians, etc. anything other than weapons see Child Prodigy - they're usually far happier with their situation (at least in fiction. Real people forced into being wunderkinds often suffer emotional trauma and burn out before they hit thirty).
Possibly Gopher; appears to be young, is explicitly called a tool by his creator Noah, and currently holds enough firepower to stand up to Maka Albarn for a while. Not long, but his comments about his body having been 'created' could make a future upgrade possible.
Anti Heroic example in Hades Project Zeorymer. The OVA begins with the protagonist finding out that his parents were paid by the government to raise him. There's a bit of Fridge Horror later on as he notes that he's their eldest child, heavily implying that he had younger siblings that would never see him again.
Mewtwo in the Pokémon anime, a genetically engineered mon who blew up an island research facility, was recruited to work for Giovanni, then got fed up and blew up Giovanni's secret Gym base.
Kirika Yuumura and Chloe from Noir were assassins trained from birth. As young teens, they have no problems with killing people. (In fact, Kirika was killing people at age five, some of them being Mireille's family.)
The titular Claymores are usually child survivors of Youma attacks, the theory being that they have nothing to lose and have the motivation to become the Organization's pet Youma killing machines. Later it's revealed that the Organization occasionally unleashed Youma on human settlements so they could conscript any surviving female children.
Also Pinochio, though the trope is inverted in that he is raised by terrorist leader Christiano as an assassin, but Christiano becomes attached to Pinochio as a surrogate son and tries to save him from the internal disputes that cause his own downfall.
From season 3, we get a rare example of Tykebombs done right. Jail Scaglietti's Numbers were all grown, turned into cyborgs, and used as assassins by him. But they all appear to have genuine loyalty and affection for him, so apparently he wasn't raising them with the 'horrible abuse' school of tykebomb training. He was also pretty good with mind control, so he might have just programmed them to like him...
Jail later tries to claim that Fate is Not So Different from himself and her own abusive mother since her adopted children have become soldiers utterly devoted to her. While Fate is unable to properly respond, her children rightly call out Jail on his bullcrap.
Erstin from Mai-Otome is a rare example whose loyalty was not abused, and who never changed sides, though she was sorely tempted and it broke her heart.
There are no fewer than threetykebombs in Mai-HiME, from two different factions. One escaped at an early age ( Natsuki), but the others ( Mikoto and Alyssa) are still active when the series unfolds....
In the manga version of Yu-Gi-Oh!, Ryuji Otogi (probably known better by his dub name, Duke Devlin) was raised from birth by his father to exact revenge against Yugi's grandfather for a Dark Game that he had lost, causing him to age several decades in one night as a result. Otogi never realized this plan until he was actually coerced into challenging Yugi to Dungeon Dice Monsters, and his father's plan ultimately failed. (The story was changed considerably in the anime; in fact, the story in the manga probably offers a more logical explanation for Otogi's Heel-Face Turn than the anime did, something that fans of the anime often had a problem with.)
In One Piece, eight members of the secret government organization Cipher Pol #9, were trained from young ages the martial arts known as Rokushiki (Japanese for "six powers"), pushing their bodies to superhuman levels for the purpose of carrying out covert assassinations in the name of the World Government. Most notable of the group is Rob Lucci: so fearful that legends have been made of him from his efficiency, coldness and brutality to the point that it not only was believed he was the least likely of the group to ever be defeated, but can survive a Buster Call, which to put into perspective razed an island.
Even the protagonist, Monkey D. Luffy and his brother, Portgas D. Ace were technically Tyke Bombs. At least with Luffy, it was revealed that his inhuman strength, stamina and outright Determinator status was the result of his grandfather, Vice-Admiral Garp throwing into deep ravines, cliffs and exposing him to high altitudes by tying him up to helium balloons, all for the purpose of making him a strong Marine (likewise with Ace). Ironically, when Garp's back was turned (for several years, apparently) they ran off to become powerful pirates which even caught the World Government's attention. Had Lucci known that Luffy was trained by Vice-Admiral Garp, maybe he wouldn't have taken him so lightly, and then it wouldn't seem such a surprise when he rises from your best attack ready to retaliate.
In the OVAKite, the main villains have a pattern of adopting orphans, raising them, ritually molesting them, and deploying them as Tykebombs for hire. The protagonist is one of their creations, and it's shown that her master made her an orphan, while she watched. It's pretty ill.
Eve from Black Cat, who was raised from childhood to become a bioweapon.
In the manga, it's revealed that Train was raised to become a killer as well... by the person who killed his parents. And Train specifically sought out training from said assassin so that Train could avenge them one day.
Every diclonius in Elfen Lied, despite being little girls, have enormous psychic power. This coupled with constant abuse and being ostracized from normal humans as well as a predisposition towards killing said humans (this may be a side effect of the abuse) creates a tragic and deadly experience for all.
The manga makes it very plain that diclonius have a built in urge to kill normal humans. Nana, the only one that consistently resists this, is actually called a "traitor" by another diclonius precisely for this reason.
Special mention goes to Mariko, who was put into a completely sealed armored container with tubes for life support inserted into her, just days after her birth, and freed for the first time when she was six years old. She even came with a safety shut-off in the form of remotely controlled explosive charges implanted in her body.
In Hunter × Hunter Killua Zoldyck was raised to be an assassin and eventually become head of his family of assassins.
Repeatedly acknowledged by Killua himself throughout the series.
Arguably, in Dragon Ball Z, Piccolo kidnapped and trained Son Gohan for a year to be a tykebomb against the oncoming Saiyans, and perhaps if he can use him against his father, Son Goku when he returns from his almost literal Training from Hell. However, he grew fond of Gohan over the year, and although Gohan was vital (and would especially be in later sagas), the Saiyans were too strong and it ended up with Piccolo sacrificing himself to save the boy.
Played a little more straight with Frieza taking on Vegeta as a child. Admittedly Vegeta decided to switch sides a bit prematurely and thus wasn't exactly a threat to Frieza when he did, but when you consider the fact that Frieza's eventual demise was at the hands of Vegeta's son, the whole thing still seems rather ill advised on Frieza's part
Played even straighter with Son Goku - sent to Earth as an infant with the intention that he would wipe out the inhabitants as he grew up. Derailed when the first Son Gohan dropped Goku on his head by accident, "defusing" him.
In season 2 of Code Geass, Rolo Lamperouge turns out to be a tykebomb. His lack of experience beyond doing his duty (and being rather psychotic) makes him easy pickings for being manipulated and suborned by the very person he was sent after.
The Geass lab, where countless kids were raised as human weapons with their Geasses. And that's actually where Rolo comes from. In the infamous raid of R2 14, at some point Rolo is seen greeting the children with a sweet smile... and shooting them dead immediately afterwards.
Emperor Charles. His entire kingdom is run by his children, who he raises to be loyal... or dead. Kinda doesn't work when his three most competent children try to kill him, including one whom succeeds in doing so. Even Euphemia doesn't like him.
The Amestris government in Fullmetal Alchemist did this for a group of babies. They were raised to become the puppet ruler of the nation, and when they became old enough, they were injected with a Philosopher's stone. The survivor was named King Bradley, and made ruler of Amestris only subservient to the real ruler Father.
Allenby Beardsley from G Gundam. She *hates* being a Tykebomb for her government, trained ever since she lost her parents, and actually falls for Domon Kasshu because he's the first one who sees her as a normal girl, not a human weapon.
Triton Bloom aka Trowa Barton from Gundam Wing, a Child Soldier raised by mercenaries after his parents's deaths and his sister's disappearance.
In the Mobile Suit Gundam SEED Stargazer sidestory, Villain Protagonist Sven Cal Bayan is revealed to have been taken from his mother and father as a young child and raised alongside dozens of other boys and girls to be one of Blue Cosmos' elite troopers. Having undergone Training from Hell since a young age, he is one of the highest scoring Natural aces of the Second Bloody Valentine War.
Also, many characters from Gundam 00. More exactly: Setsuna F. Seiei, Allelujah Haptism, the three Trinity siblings (Johann, Michael, Nena), and Marie Parfasy/Soma Peiris. Incidentally, FUCKING RIBBONS has a lot to do with making all of these examples.
Cossette, from the Excel♥Saga anime, was raised to become an assassin after her mother's death, with the verbal abuse included. She gets better with help from the Great Will of the Universe that revives her mother. Later on, she becomes an assassin again because she likes the smell of blood
Rei and Asuka from Neon Genesis Evangelion. Rei was intended to pilot EVA from the beginning among other things, while Asuka was recruited from a very young age.
Shinji himself is the ultimate example of the trope. Gendo sends him away, and when he comes back taunts him and alternates between showing some humanity and treating him like shit precisely so that Shinji will hate him and direct his feelings towards his mother Yui, whose soul is inside the Eva, so that he can "synch" with her and eventually trigger Third Impact on Gendo's terms. Things dont go quite according to plan.
It goes even deeper then that since Yui planned to make her son into this before she even frickin knew who his father would be. It's implied she married Gendo because of his messed up and easy to mold personality so the chanses would increase for their child to be an emotional wreck. She specifically wanted Shinji to witness her own death to traumatize him, and Gendo's horrible treatment of him was exactly how Yui wanted it. This was all to make Shinji a messed up, hyper vulnerable kid that would have the best chanse to trigger the EVA's unbeatable berserker mode. Wich he does better then anyone Seriously: The woman IS NOT HUMAN.
A rare example from the (nominal) heroes, Omi Tsukiyono from Weiss Kreuz was rescued from abduction as a child by his handler, Persia, only to be raised as an assassin by him with the intention Omi would then be sent to kill Reiji Takatori, the father who abandoned him, who was also Persia's older brother. Unfortunately for Persia, Omi's paternity turned out to be rather less clear-cut than he'd imagined and he turned out to have trained his own child to be a conditioned killer. And these are the good guys.
Flame of Recca is almost a perfect illustration of why you should treat your Tyke Bombs properly. The Big Bad, Mori Kouran, secretly created dozens of genetically-engineered clones of his Dragon Kurei, spliced together with genes from his own daughter, Kurenai, in an attempt to create a servant that would have Kurei's terrifying flame powers, but that Kouran could go to sleep around without worrying that he would wake up with his face burnt off. Only two of his creations survived: A girl, Renge, and a boy, Aoi. Renge had flame powers and childlike simplicity, exactly what Kouran had been looking for, and so he adopted her as his daughter and spoiled her with praises. She remained loyal right through the end of the series, up until when Kouran killed her and absorbed her flame powers in order to give himself resistance to the protagonist's similar ones. Aoi, on the other hand, did not have flame powers, and so was considered a failure. He was treated like garbage, and although he did serve Kouran faithfully through most of the series (trying desperately to prove his worth), in the end The Power of Friendship causes him to perform a Heel-Face Turn.
Several characters in Monster were orphans chosen for a psychological experiment attempting to create "perfect soldiers," which went catastrophically wrong. The titular character was even involved in two of them, having been born from parents who were paired off as the first stage of a eugenics experiment.
In a way, the experiment can be seen as going catastrophically RIGHT. They wanted the perfect killing machine, and they got Johan
Gaara whose Tykebombification went a little too well...
Apparently Naruto himself was set up in his rather sucky position because the fourth Hokage (his dad, Minato) knew the Big Bad unleashed the fox on Konoha, and knew whoever was going to deal with it would need some extra power, so he sealed a gigantic rampaging monster into a baby Naruto, who is not happy about this. Bonus points for being sort of justified, though, as Minato truly had no option about that.
Many (if not most) of Orochimaru's subordinates could be considered tykebombs, as it appears that he find many them as children, often orphans, and raises them as fanatically loyal soldiers. Some he chose because they already possessed useful special abilities, and others he modifies, either genetically, through the curse seal or by providing them with weapons, sometimes implanted like those of the Sound ninja that participated in the Chuunin exam.
Root also recruits a lot of their members young, especially orphans.
Yamato was the only survivor of a program (headed by Orochimaru, before he left Konoha) to infuse an infant with the First Hokage's bloodline ability.
Sousuke from Full Metal Panic!, being taken in by the KGB at 5 years old, was raised to be an assassin. And then he got taken in by Majihd to become a guerrilla at the age of 8. And after that, up until his current life (16 years old), Kalinin had trained him even more. This is one rare instance, however, where he generally wasn't treated badly by the people who raised him to be a human weapon. Lampshaded in the novels, where he actually thinks to himself that he had been aware that he was always treated gentler and nicer by the other soldiers and fighters because he was pretty.
Balalaika, the woman responsible for putting the aforementioned Creepy Twins down, was ironically a borderline example herself — she was raised by her grandfather to be the perfect soldier, and shipped off to fight in the Soviet-Afghan war when she was barely out of her teens. Flashforward a decade, and she's the leader of a vast criminal empire — and completelyinsaneto boot.
In Black Butler, Finny was one of these, until he escaped and went to work for Ciel Phantomhive.
Witchblade presents the whole mildly disguised Tykebomb Factory and glimpses of their lives, in several variants up to trying to self-defuse. This life doesn't prevent possible unrelated awesomeness even for ones far enough from any human norms, but apparently more often than not it sucks to be a Neogene. This may have something to do with the head of this project (and consequently the true purpose) being batshit insane.
In Bleach the Big Bad revealed that Wonderweiss Margera, a very childlike arrancar, was modified to be exactly this, exchanging his ability to speak or reason for pure power. In something of a play on words, he explodes on his defeat.
A non-fighting version appears in Captain Tsubasa. A former Doorstop Baby, Carlos Santana became this after his adoptive parents died and their boss forcefully recruited him, subjecting the kid to Training from Hell for several years until he became the "God of Soccer". He gets defused by Tsubasa and his friend Luciano Leo, though. And in the original manga, he's reunited with his Missing Mom.
Seta Soujiro in Rurouni Kenshin, but it's complicated: a two-step process. First, the kid ends up in the custody of a completely monstrous foster family who abuses him to no end, conditioning him into a Type A Stepford Smiler. Then he happens upon Shishio Makoto, having just survived a Kill It with Fire attempt. The creepy burn victim is the first person to actually acknowledge the kid as something significant, so they hit it off, allowing for the second phase to kick in and Soujiro to kill his foster folks and follow Shishio. He's eventually defused when he's defeated by Kenshin because his Pacifist philosophy clashes with Shishio's, prompting him to take a page from Kenshin's book and become The Drifter so as to resolve the mental conflict.
In Tiger & Bunny, Albert Maverick had a spare NEXT kid on his hands after murdering the kid's parents. Not wanting to let things go to waste, he used his own NEXT powers to doctor the kid's memory a bit, set himself up as their Parental Substitute, and raised the child in a manner that would guarantee their fierce loyalty to his cause. This child was Barnaby Brooks Jr.
In Attack on Titan, Annie Leonhart, Reiner Braun, and Bertolt Hoover are heavily hinted to have been trained from an early age for their mission. Eren Yeager becomes one, of the laser-guided variety.
The original members of the Runaways were bred to take over for their parents, to inherit the Earth and their parents' power. It did not go well. For irony, the children rebelled because their parents had treated them well, since the children grew up with healthy consciences. Thus, they wanted no truck with parents who ritually murdered other teenagers and were willingly serving monsters who intended to wipe out all life on Earth.
More literal tykebombs existed in the recent Sinestro Corps War in the Green Lantern comic books. The so-called "Children of the White Lobe" are psychokinetic children raised from birth to be fanatical terrorist suicide bombers, and who make use of a mineral that becomes extremely explosive when stimulated by psionic powers such as their own—usually by swallowing a small chunk and then setting it off when the time is right.
Third Batgirl Cassandra Cain was trained from a young age to be an assassin. She was horrified by her first kill, and ran away. She subsisted on the streets, until encountering Batman and his allies.
Similarly with Damian Wayne, Bruce and Talia's son. He was trained from an early age to be a warrior. The difference between him and Cassandra is that she was treated as a weapon. Damian was treated as a prince, spoiled rotten and able to do whatever he wants. Even as Robin he's the most violent, surpassing even Jason Todd. Of course, spending time with DickGrayson (who he initially served as Robin under, not Bruce) has softened him up quite a bit.
From the comic mini-series/2010 movieKick-Ass, the backstory of Hit-Girl was that she was over-trained at an early by her vigilante-minded father to grow up akin to Batman. Though it must be considered that in the comics, the "defected cop whose wife was murdered" story was made up by Big Daddy. The motivation for turning his daughter into a killing machine was not revenge, but simple fun.
The Strafenkinder in The Books of Magic, sort of. The Margrave entices young, unhappy boys with lies and gifts, give them a fancy uniform and neat badges. And then send them back to their parents to explode. A few of them can put themselves back together afterwards, but the Margrave doesn't seem too concerned about those who don't.
Michana Loomis in Nexus. Paradoxically, despite her older sister Stacy's best efforts to laser-guide her, she ended up saving Horatio from Stan in their final confrontation.
Also Horatio's own daughters, since they were conceived by Ursula expressly for the purpose of inheriting Horatio's powers, and raised by her to be warriors. They ended being good anyway though, and saved Horatio from the Loomis sisters.
As recently revealed in the Knights of the Old Republic comics, Lucien Draay was raised by Haazen in this way as part of his revenge on Lucien's father Barrison.
This was Demagol's big pet project. He wanted tried to take DNA from Master Arca, an Arkanian Jedi and grow his own test tube Jedi for the Mandalorian war effort. He spliced master Arca's genes into children and sent them off to the Crucible to be trained. Jareal was one of the children from this program.
All the Judges in the Judge Dredd universe start their training around age 6 or so (possibly earlier).
In at least one story, the age is stated as 5 years old.
Red Skull seemed to be heading down this path in the Ultimate Universe - the illegitimate son of Captain America, he was taken from his mother and raised by the United States military, and proved to be leaps and bounds a better soldier than even his father... And then he killed everyone on the compound and cut off his own face. At seventeen.
Thanos from Marvel Comics and Gammora. Thanos raised a daughter from childhood to have a perfect assassin. As a subversion he did try to otherwise be a decent father to her, though she rebelled anyway.
Dreadstar's daughter was a very straight example, and a major plot point of the second series.
Present in Garth Ennis' The Boys in the form of the G-Men: "gifted" children selected from orphanages note read- ordinary kids snatched from the street by the nice man with the toys and candy and big shiny black limo and trained note injected with the potentially fatal mutagenCompound V and repeatedly sexually abused by John Godolkin and the senior members of the G-Men to become superheroes. Also implied in a less creepy fashion with those supes whose powers were the result of pre-natal/parental exposure to the setting's Super Serum, with foster parents raising and training them in a manner reminiscent of the culture around (child) beauty pageants.
Prior to meeting up with Batman and becoming Batwing, David Zavimbe was a frighteningly effective child soldier.
One issue of the limited series Muties featured a boy named Riek who suddenly developed the ability to manipulate time while serving with a Lord's Resistance Army expy.
Common in the Star Wars galaxy, like the Jedi Order, the good guys. Also included are Darth Maul, selected and trained from the time he could walk, the Grand Army of the Republic, technically about 10 when they're sent out to fight due to their 2x speed growth rate, and Galen Marek, anyone?
Jedi are supposed to be taken for training at an early age, specifically to ensure all they know is the Jedi way and they do not form attachments to anything or anyone outside it. This has... raised eyebrows, even in-universe.
Lady Snowblood was conceived by rape and raised as an assassin from birth by an abusive monk solely to avenge her dead mother's murdered husband and son. From Bad to Worse.
In the beginning of The Departed, crime boss Frank Costello carefully grooms the young Colin Sullivan into becoming both staunchly loyal and respectable enough to become a highly-respected officer in the Massachusetts State Police. This was reflective of the actual events involving crime boss James "Whitey" Bulger and old neighborhood acquaintance John "Zip" Connolly, but in Real Life, the age gap between them was considerably smaller, and they didn't really concoct their scheme until both were into adulthood.
Miss Havisham from Great Expectations was left at the altar and swore revenge against all men, so she adopted a baby girl named Estella and raised her to be a sociopathic heart-breaker.
Arguably Ivy from The Dresden Files. She is a living repository of all human knowledge, has no choice in the matter, should avoid any close emotional attachments and because of the death of her mother, acquired this awesome responsibility while a very young child. In fact, until she met Harry, she didn't even have a proper name, just the title of the Archive. Her only regular companionship is her bodyguard Kincaid.
Harry himself, or at least it's implied Justin's plan was to make him and Elaine this. It's debatable, actually, if a little of the conditioning seeped in. At the very least it impacted Harry's life significantly and gave him major trust issues (doesn't help that those issues are reinforced every other book).
The setting of most of Ender's Game is essentially a Tykebomb factory. Ender in particular is abused and pushed to his breaking point, just like the standard tykebomb, in an attempt to create the perfect commander. Since he believes in the cause, it works.
In the Discworld novel Sourcery, the wizard Ipslore the Red raised his son the "sourcerer" (a source of magical power, and much more powerful than wizards, who just manipulate it) to conquer the Unseen University, and then the world. Coin is expected to do this at the age of ten, and manages quite well before Rincewind Defuses him with his utter, comical harmlessness.
A form of this occurs in Inkheart. Capricorn knows that the best age to recruit his fireraisers is in their early teens. After all, "there's a lonely boy who likes to play with fire in every village". He despises all his men, thinks of them only as tools, and generally treats everyone like crap, even sentencing his most loyal man to be killed by the Shadow for the crime of "stupidity".
Moke in Star Trek: New Frontier was not raised to be a Tykebomb, but he turned out to be one nonetheless. Moke is not the name his father would have given him. He'd have picked something more traditional like... Thor
Falcone in Warchild made it his personal mission to make an army of tykebombs, his "protégés". He figured a soldier raised from a young age would be absolutely loyal to him. And if they went out and made their own protégés, these in turn would also be loyal to him. After a couple decades, he'd have an army of trained soldiers with no qualms about following his orders. Unfortunately (well, for him, not so much for the kids he manipulated), no one told him it might be a bad idea to sexually abuse those kids he obtained. Of the four he tried to create, one was rescued by a Space Marine and became his greatest enemy, another killed himself, the third escaped and later murdered Falcone rather than see him escape. Only the fourth was loyal for any length of time.
The Mouse Army in The Diamond Age. And there's lots of them. Although it isn't entirely clear whether they were intended for good or nefarious purposes originally.
Bonus points—it was originally intended, by the people saving them from orphaned death in the turmoil-ridden interior, that they simply be raised as normal girls, albeit normal girls who grew up entirely aboard giant offshore ships devoted to the purpose. The agent of tykebombification was the pseudo-AI Great Big Book of Everything that was duplicated en masse to raise them—and the engineer who made both the original (intended for the granddaughter of a hyper-rich neo-Victorian aristocrat) and the many copies altered the copies, under the pretense of making them more 'culturally appropriate' for the Chinese foundlings, to semi-condition them into complete loyalty to the holder of the original. Apparently for the lolz.
The Vorkosigan Saga: Mark. Over the course of several books, there's a lot of character development with him learning to be his own person away from the purpose his obsessive father created him for.
Actually, a frequently-recurring theme in that series is genetically-engineered people who turn out not to be as obedient or predictable as their creator expects: the quaddies in Falling Free, Taura, the ba in Diplopmatic Immunity, etc.
In Dune Messiah, the conspiracy against Emperor Paul Muad'Dib created Hayt to assassinate him. Later in God Emperor of Dune, the conspiracy against the God Emperor Leto II created Hwi Noree for the same purpose. Leto himself created gholas of Duncan Idaho for companionship; most of them rebelled against him.
In Paul of Dune, Lady Margot and Count Fenring train and educate their daughter for the sole purpose of assassinating Paul Maud'Dib and taking his place.
In the Andrew Vachss Burke book Dead and Gone, Burke learns near the end that the child he had been tasked with retrieving had been kidnapped, indoctrinated and trained as a killer by Neo-Nazis. Said child would have gotten the drop on him if he had not been wearing a Bulletproof Vest.
A Bomb Built in Hell, Vachss' first novel, exemplifies this trope. Wesley, the "bomb" from ABBIH, makes acouple of appearances in the Burke series.
The Howlers of the Animorphs series were eventually revealed to be a race of carefully engineered tyke bombs. Having no concept of pain, defeat, or empathy, they fought against their enemies with a childlike joy. They were eventually ruined when the concept of "love" was spread into their race's Hive Mind.
In Firestarter, Charlene McGee is a powerful pyrokinetic due to her parents being test subjects for a substance known only as Lot 6. The Shop, who developed Lot 6, hoped to train up her psychic powers to turn her into a weapon, but they severely underestimated just how much a 7-year-old girl loves her daddy.
Sicarius in Emperors Edge has been groomed from birth to work as an assassin for the (now former) emperor, and managed to survive to his early 30s and extreme competence at killing people, but an utter lack of social skills.
In the Redwall installment Taggerung, the Juska tribe steal a baby otter from Redwall and raise him as a prophesied warrior. It doesn't work.
In Century Rain, the Slashers produced huge numbers of specially-engineered child soldiers during their war with the Threshers a decade or two prior to the novel. This becomes important when it turns out that the alternate Earth was being heavily manipulated by a faction of the Slashers, with many of their agents being said soldiers. The presence of creepy, not-quite-right children is one of the first clues to this being the case.
Jeremiah in Someone Else's War is the product of rape, born to a female slave held captive by the LRA. He has been a soldier since the moment he could walk and understands little else but warfare. Sad case of Truth in Television.
The Career Tributes from the districts 1, 2 and 4 in The Hunger Games are raised from childhood to become warriors in the annual Hunger Games.
Eppon in Galaxy of Fear, in a sense. The heroes find him as an infant and he grows very rapidly to adulthood - as per the plans of the Big Bad, to whom he's loyal.
Jacob Ricel in Diane Duane's Harbinger Trilogy. Just to make things more fun, he's actually one of several clone siblings raised together by the evil corporate star nation.
Sinfjotli in The Saga of the Volsungs is conceived and raised for no other reason than to exact vengeance on King Siggeir.
In Animal Farm, Napoleon has the foresight to take a newborn litter of puppies under his wing. They eventually grow up to be fearsome and totally loyal enforcers.
The execrable 70s sci-fi novel I, Weapon is about a breeding program to create the ultimate human weapon, crossbreeding human subspecies. And then he goes on a mission that is best described as trippy.
Adria in Stargate SG-1 is a genetically engineered child that the Ori made in order to have a messenger in the Milky Way without dealing directly with the Ancients. She was also engineered to not stay a child for long.
In the first season SG-1 found a literal Tyke Bomb which would blow up the second she was returned to her home planet. She was adopted by Dr. Frasier.
Max and her sibs from Dark Angel were created with cat DNA mixed in and trained from birth to be soldiers before escaping and turning against their former "sponsors."
The series Angel had Connor kidnapped only a few months after his birth and raised to his late teens in a hostile dimension, taught to become the ultimate opponent against his birth father.
From the second season of Heroes, Elle Bishop, after her electrical powers manifested, was subjected to extreme electrical torture to see how much she could take. By her own father, no less. The end result is a sadistic and insane girl whose father sends her out in the field, referring to her as an "executioner."
The Jem'Hadar are not quite a straight-up example, as they're not necessarily mistreated by their creators, nor are they ruled over irresponsibly, and thus have pretty rock-solid loyalty. This loyalty, however, is achieved through an engineered, in-bred drug addiction; when they run out of that drug, they run the danger of playing this trope straight-up.
The Remans of the Romulan Empire in The MovieNemesis are a much more straight-up example, especially since they are essentially ruled by a kid.
Alpha and any other doll in Dollhouse, in a sense, given that they are implanted with a full set of memories going back to infancy when they are imprinted for engagements, despite having signed their bodies over to the Dollhouse as adults. An Active can thus have a lifetime's worth of training as a thief, assassin, or soldier.
The Cortexiphan children in Fringe were given drugs at extremely, disturbingly early ages in the hopes that they would develop superpowers to become weapons in a potential war against another universe. In most cases, this left them as ticking tyke bombs.
Icheb from Star Trek: Voyager was genetically engineered to produce a virus that would destroy any Borg cube he was picked up by.
Star Trek's Borg are bred into the collective artificially, in addition to assimilating others.
Scorpius on Farscape was part of a Scarran breeding program designed to improve the species by blending it with other races; he was not considered a success, partly because of the health problems he suffered from, but mostly because he stabbed his nanny's eyes out and joined the Peacekeepers. Sikozu is another example, having been genetically engineered to kill Scarrans as part of the Kalish resistance movement.
A recent episode of NCIS had one as the criminal of the day.
In Doctor Who, Madame Kovarian kidnapped Melody Pond, Amy and Rory's daughter to raise her as a tykebomb against the Doctor. Considering Melody is seen in later life as an Action Girl with a mysterious and dark past who makes Daleks beg for mercy, is a convicted criminal (in a Cardboard Prison), and admits to having killed a "good man," it looks like this plan might have succeeded.
The Salamanca twins Marco and Leonel from Breaking Bad are a textbook example - a flashback shows them fighting over a toy, chaperoned by their uncle Hector - to resolve this conflict, Hector drowns Leonel, forcing Marco to hit him as hard as he can in order to save his brother. As adults, they are silent, brutally efficient killing machines and textbook Determinators.
In Exalted, the Deathlord known as the Dowager of the Irreverent Vulgate in Unrent Veils only has one Abyssal Exalt: a young girl called the Shoat of the Mire, who is always a member of the Dusk Caste, the Abyssals' ultimate warriors. Since Abyssals are usually stuck at the age they Exalted at, the Shoat will remain a young girl for the rest of her existence. Should one Shoat die, another will take her place.
House Xorlarrin of Menzoberranzan used to start early arcane training for all male offspring with high magical talents (by the way, other male children are either sacrificed or sold).
Halruaa got Jordain, anti-talents their order raise and train from very young age. With amount of The Masquerade surprising for such a presumably nice place. When in Counselors and Kings one of them discovered how they are really created and saw what happens to their mothers in process, he mentioned it's good that his wizard dad is anonymous—he'll probably live longer this way. That's not counting some... "little details" (or rather lack thereof) concerning Jordain themselves.
The Space Marines of Warhammer 40,000 are chosen for initiation prior to adolescence. While that is plenty of time for them to be used to other opinions, they train and fight for decades before becoming a versatile Tactical Marine, leaving a likely similar effect. They'll have been experienced killers long before being chosen for initiation anyway.
The Assassins' Guild does this in the Guilty Gear series, taking in children orphaned by Gear rampages and the like. Among these children, Millia Rage became the dog that bit back, only it's kind of subverted in that she somehow saw a life beyond killing the whole time. The exact specifics of that waver due to the games' plots not being as import as their rock and metal references.
Metal Gear does this a lot, although usually deals with the psychological repercussions, too. Raiden was six years old when he held his first AK, the three Snake triplets were all raised from their cloned conception to be extremely good soldiers, and in Portable Ops Gray Fox is revealed to have been raised in a twisted isolation tank as part of the 'Perfect Soldier Project'.
Meanwhile, Revolver Ocelot (ADAM), called "Adamska" by his fellow Russians, as well as Big Mama (EVA). Both were trained from young ages to be Super Soldiers, as well as to blend perfectly into various nationalities. Ocelot, being half-Russian and -American, could act as a spy for either country with relative ease. EVA, meanwhile was raised by the Chinese and trained to act and speak flawlessly like a American. In The Last Days Of FOXHOUND, this is spoofed with Ocelot's lines: "I've been working for [The Philosophers] since I was born," and "I've been trained to be an X-Tuple agent from the age of four."
Big Mama's resistance group consists entirely of war orphans whose only goal in life is to fight without any oner interests.
For an example made by the good guys, the main character and the rest of the SPARTAN-IIs of the Halo series were trained as a warrior from the age of six and have been continually fighting since they were fourteen, but at least they were intended to survive into adulthood. The SPARTAN-IIIs, however, were purposely trained to be prepubescent suicide troops: only a handful of Alpha and Beta Company survived past childhood, mostly the ones who were considered gifted enough to be transferred to more elite units. Of those who remained in Beta, only two survived, while no one who stayed in Alpha made it.
The Vanguard bloodline of Bloodline Champions are stated in the background to be trained after being chosen in childhood.
Final Fantasy VI has Celes and Terra. Justified in Celes's case, as the Magitek infusion process is said to be incredibly dangerous and painful when used on an adult. The last one they tried it on was Kefka, and that didn'tturnoutwell.
Terra herself was captured as an infant and raised as a tykebomb due to her natural gifts.
Sephiroth from Final Fantasy VII. He was engineered by Shinra scientists to be the perfect soldier, implanted in the womb with alien DNA to endow him with superhuman strength and intelligence. The procedure killed his mother in childbirth, though she remained Not Quite Dead. He was then raised by his "surrogate" father (who never told him they were actually related) and grew up to be one of the world's most famed war heroes... until he discovered (most of) his secret origins, went Ax-Crazy, and decided to destroy the planet and become a god in the process. He damn near succeeded.
Sephiroth's remnant, Kadaj, also qualifies. After Sephiroth's defeat, he wills this guy (and two others) into existence with the mentality and appearance of a teenager, for the purpose of insinuating Reunion and bringing Ol' Seph back from the Lifestream, and sacrificing his own body in the process. It's unknown how much Kadaj actually knew of what would happen. He was programmed to press for it to happen. He also wanted his mommy, which is kind of hard to explain. Loz and Yazoo also count, but they don't get as much screentime.
Though not raised from birth, the SeeDs in Final Fantasy VIII are generally trained from a relatively young age, with the youngest accepted students being only five years old and the oldest being fifteen. Ostensibly they're being trained as supercharged mercenaries, but in reality they're being prepared to wage war against the Sorceresses.
Final Fantasy Tactics had Rafa and Malak, who had their village destroyed, so they could become these after their elders refused to let the villain use them for his own purposes. Rafa turns and Malak follows shortly.
Ramirez from Skies of Arcadia was made by the Silver Civilization to hunt down the Moon Crystals by infiltrating the Valuan Armada. Unfortunately, having No Social Skills due to his upbringing, exposure to the world beyond proved too much to him and he ended up as the Battle Butler of charismatic Big Bad Galcian - the very man he was sent to thwart.
Taken a bit further with Galcian's training and indoctrination of Ramirez (he was just young enough for this trope to still qualify). Somewhat subverted, as it appears that Galcian genuinely cares for and respects Ramirez, acting as a father figure.
In Dead Rising, Carlito is revealed to have set up adoptions for infected orphans all over America at the end of the 72-hour story.
In BioShock, the player character turns out to be a Tykebomb.
In BioShock 2, Eleanor Lamb would count, but averted it: She was supposed to be her mother's tool to fulfill her crazy utopia for Rapture and, probably, the world, and was raised to become this, albeit whether Sofia planned to take it to Combative manner prior to Eleanor's turn into a Little Sister and her turning into Rapture's New Boss is left for assumption. But thanks to some living with other kids, her mother's constant nagging and eventual experimentation, Delta's care for her while she was a Little Sister and some use of common sense, she rebelled. Still, she's one fighter. In the Bad Ending, she will evolve from Tykebomb to Woobie Destroyer of World and gets even with her mom, drowning her before she swears to destroy the world. They grow up so fast....
Elizabeth in Bioshock Infinite, of a sort. Though not raised as a warrior, she was being raised by her father, Comstock, with the intent that she would take over for him after his death and bring his plans to use Columbia to purge what he saw as the corrupt surface world. After she is recaptured by Comstock, we learn that in one reality she does just that, before a My God, What Have I Done? realization has her reach out to Booker and help him rescue her alternate self before she can be broken and turned into this.
Super Robot Wars Original Generation gave us The School, a facility that "reconditioned" children, both physically and mentally, to become Humongous Mecha pilots. Eventually, the high mortality rate(there are only four known survivors, out of an unknown number of subjects) and the development of mecha training programs that could be safely used on normal people, The School was eventually closed down.
JC Denton in Deus Ex is a clone raised from birth by "foster parents" employed by Page Industries, who are murdered by a MIB when they become attached to him and Paul. He was raised to be a nano-aug for UNATCO, who are pawns of Page Industries, until his brother, Paul (having already defected), confronts him at an airbase and persuades him to examine the details more closely. JC does so, and in the process is labeled a traitor due to his actions. He then rescues Paul from eventual demise at the hands of a killswitch, turns on his former masters with the help of what remains of the Illuminati, unifies the Hong Kong Triads (who aid him), and canonically merges with Helios (in place of Bob Page, whom Helios decided wasn't worthy) to restore order and usher in a new, enlightened age.
What makes JC's background confusing though, is that if you read some of the datacubes lying around Area 51, they imply that JC's history wasn't the one mentioned above, but instead he was born a couple years before the game, had growth acceleration, and implanted memories. If you look at the "decanting tanks" in one room, one of them have your name on it, states that you were born a few years earlier, and had a assigned birth date to you. Which is the real theory is anyone's guess.
Jaffar from Fire Emblem: Blazing Sword was allegedly found as an infant sleeping atop a pile of corpses, and groomed to be a powerful assassin by the local assassin's guild. Nino was probably a failed attempt at making one of these as well, although she turned out to be too softhearted, and in fact is who triggers Jaffar's humanity and his Heel-Face Turn.
Cynder, from The Legend of Spyro almost fits this. Her egg was stolen by the Dark Master's forces before her birth and she was raised within his evil influence, given seriously souped up powers and an adult form and sent out to help the Drk Master take over the world. And she is a total Bad Ass. Interestingly, the "Fury" attacks of Spyro (and Cynder in the third game) make them elemental tykebombs.
The Zener Children in Second Sight were meant to not only prove the reality of psychic warfare, but also to act as the first generation of psychic super-soldiers loyal to the Soviet Union. However, the project was a failure: more than half of the children who learned to use their powers successfully were hideously disfigured by their medication, and the others were judged far too disconnected from the outside world to be of any immediate military use.
Plus, in a subversion of standard Tykebomb fare, the research staff treated the Zener Children very well, and continued to do so even after the project's funding was cut.
The main character in Overlord II started out as a Creepy Child in the little town of Nordberg. The Minions eventually found him and brought him back to the Netherworld. Then Gnarl raised him for 13 years to become the Overlord that they needed. The Minions being in charge of his early development goes a long way to explaining why the new Overlord is more explicitly evil than his canonically Noble Demon father, the previous Overlord.
In FEAR, both the Point Man and Paxton Fettel were raised as these. In additional, Project Harbinger involved all of Team Dark Signal, including Michael Bekett, the player character in Project Origin were raised as psychic Tykebombs, and Wade Elementary is a school devoted to creating Tykebombs through use of drugs to generate psychic abilities.
In a way, Pokémon the player creates through the in-game breeding system. You can breed them to have optimal move-sets via egg moves and then EV train to get their stats right.
Mewtwo deserves another mention. Its story in the games involves it being the embryo of a pregnant Mew. Mewtwo was tampered and gene-spliced until it turned vicious and was made into a battling machine. It later went berserk and destroyed Dr. Fuji's Pokémon Mansion on Cinnabar Island. It then took shelter in Cerulean Cave (a place both it and Mew seem naturally attracted to).
Similar to the Pokemon example above, Sonic Adventure has given us the Chao, which, after enough breeding, can create offspring that have gigantic stat growth, to the point where a Chao of the highest grades in stats is equal to a mediocre Chao with twice as many levels.
In Mass Effect 2, there's several protagonist tykebombs: Jack, a homicidal ball of rage who was abducted by Cerberus as an infant and transformed into the most powerful human biotic; Thane, who was trained as an assassin from age six; and Grunt, a tank-grown Krogan mega-soldier, who is as violent as he sounds.
Cole McGrath, the hero from inFAMOUS could count as one. As Kessler set him up since his birth to make it so he could fight the Beast.
In Dragon Age: Origins, as part of the ending Morrigan proposes an alternative way to destroy the Archdemon without using a Grey Warden to trap its spirit after its dragon body has been killed. She will get herself pregnant by a Grey Warden so that she can destroy the dragon and the demon will be trapped in the growing child. Her only condition is, that she will disappear right after the Archdemon is destroyed and nobody will try to look for her, while she keeps the child and raises it. Since an archdemon is really a corrupted Old God, the child would be incredible powerful, whatever it might turn out to become.
It's also worth considering that the whole thing was the idea of Flemeth. She is unique in having her spirit merge with that of a demon who possessed her, whill still remaining her own self, and also one of the most powerful mages who ever lived. To prolong her life, she transfers her spirit into that of her daughters, and had the archdemon appeared a generation later, she would have done the ritual to create a child in with the Old God is bound. That child would have been a nuclear tyke arsenal.
In Syndicate (2012), unlike the original where Agents were civilians taken off the street for conversion, Agents are now recruited and trained from young. However, they don't get sent on operations until older, averting Child Soldiers.
The vampire Kagan in the BloodRayne series makes this standard policy for all of his offspring: He rapes human women, and once they give birth slaughters their entire families so the child has no one to turn to but him. He then raises them to be his loyal minions and the leaders of his plans to blot out the sun and conquer the world. Not that it stops them from trying to back-stab each other, however. Rayne herself was rescued and raised by fully-blooded humans before Kagan could get to her, and ironically was turned into this as a weapon against her father.
In Resident Evil, Project "W" was Oswell Spencer's first and grandest attempt to replace humanity with a superior breed. He infected many children with the Progenitor Virus, the original mutagenic virus that spawned all of Umbrella's other horrors, and indoctrinated them with his values. Albert Wesker was one of the only survivors. He didn't take it well when he found out he was essentially manufactured and thus never really had any control over his own life.
Miles Edgeworth in Ace Attorney had a happy, normal childhood until he was eight years old and his father was murdered. He was adopted by Manfred von Karma and raised to be a perfect, ruthless prosecutor who would do nearly anything for a guilty verdict specifically because von Karma hated Edgeworth's father so much that he not only murdered him, but spent fifteen years twisting his son into everything Gregory Edgeworth stood against. Why? Because Gregory Edgeworth made him take a penalty in court.
Ilya in Fate/stay night, raised from around the age of eight to take part mercilessly in the Holy Grail War and to hate her father for abandoning her, though in truth he always tried to go back to her and the Einzberns would not allow it. So now she has mixed feeling of wanting love from Shirou and wanting to dismember him for being her father Kiritsugu's adopted son and seemingly taking her place. Shirou can never truly bring himself to see her as an enemy even oblivious to the circumstances.
Sakura is revealed to be this in Heaven's Feel. Like Ilya, she was developed to be Matou's own Grail vessel, with Training from Hell just as physically and psychologically abusive, but much more demoralizing.
Arcueid Brunestud of Tsukihime was bred to be the strongest (and purest, without the innate desire for blood that plagued the rest of her race) of the True Ancestors, with the intent of having her hunt down their fallen brethren who had become insane blood drinkers, and the Dead Apostle vampires that they had spawned. In a slight twist on the trope, they had fully intended to give her a proper education and a normal (by True Ancestor standards, anyway) life after she'd finished her job, and had in fact started on doing so when things got out of control.
In Homestuck, the Handmaid (aka Aradia Megido's ancestor) was raised from a grub by Doc Scratch in order to be a servant of Lord English. Under English's orders, she sowed chaos throughout Alternian history and became regarded as a demon.
Bell from the Powerpuff Girls Doujinshi is strongly hinted to be one of these. Project Rowdy also seems to be a government project that resurrected the Rowdy Ruffs to serve this very purpose (the Ruff resurrection happened before the canon resurrection by Him, which explains the difference).
Ninja Blankfaces in Sam and Fuzzy are raised from birth as assassins loyal to the upper echelons of the Ninja Mafia.
Oasis from Sluggy Freelance was raised by Dr. Steve to serve as an assassin and a tool for his plans. He avoided many of the problems by just brainwashing her somehow, which has also prevented the good guys and herself from successfully defusing her.
Ilivais X has its Tyke Bomb, Iriana, rebel from the very start. Even though she's 17, she was designed to remain in a child-like form forever, adding to the very large lists of complexes she deals with over the course of the story.
Phaeton has Nakira Mite, she was however mind wiped and remembers nothing before her last reprogramming, but the muscle memory is still there. Many of the orphans we haven't seen are iplied to be this too.
Danny Phantom had one villain attempting to clone Danny, in the process creating Danielle, an "imperfect" (younger, female) clone who had his powers but risked clone degeneration by using them. She stayed loyal to the villain... until he told her to her face that he didn't care about her except as a stepping stone to create a perfect clone of Danny. To be fair, he didn't realize she was there.
Slade from Teen Titans had designs on grooming Robin into a Tykebomb. When that failed, he moved on and succeeded with Terra. Then he pushed her too far and suffered the aforementioned explosive retaliation.
Mai learns that her father plans to invoke this trope with her little brother Tom-Tom in the comic Rebound. She quickly puts a stop to it before it can begin.
The Justice League episode "Wild Cards" features a Tykebomb of sorts in the form of Ace, who was raised to be, essentially, as terrifying as possible. The Royal Flush Gang in this episode is arguably a mega-Tykebomb. In Justice League the Gang originated in Cadmus, whose specialty is creating and raising up super-powered opponents just in case the League starts abusing its power or, as the case may be, Lex successfully schemes to make it appear as if the League has. From their (chronological) introduction in this episode, they go on to become a staple of the Batman BeyondRogues Gallery.
Teenage Mutant Ninja Turtles character Karai is turned into one of these in the 2003 cartoon. An orphan found and adopted by the Shredder at an early age, he turned her into one of his most loyal and capable lieutenants. The Shredder, surprisingly enough, turns out to be a rather good parent (at least from her account) and the ensuing loyalty she feels to him is at the core of her character arc.
Hana, Ron's adoptive baby sister in the 4th season of Kim Possible. In the prophecies about her, she's even called "the weapon".
Superboy in Young Justice. He has Superman's strength and speed but lacks the discipline to use them properly. He has some anger issues that needs to be worked out and the part where his "father" Superman doesn't even acknowledge him makes him more upset and frustrated. He disrespected Black Canary, believing that he could win any fight based on his power and can be fairly harsh on his teammates. But he is learning, now respects Black Canary (after she made him swallow his words) and is more friendly with the rest of the Young Justice.
The Legend of Korra has Yakone raising his sons, Tarrlok and Noatak, as his instruments of revenge on Aang and Republic City by teaching them Bloodbending and drilling this idea into their heads. Even though Noatak betrays him, ironically, it works. Tarrlok becomes a corrupt councilman and Noatak becomes Amon.
Season 2 introduces us to Eska and Desna, Korra's twin cousins, who while not explicitly raised this way by their father Unaloq, are incredibly powerful Waterbenders, emotionally detached from everything, and almost blindly loyal to their father's plans.
If the twins count, then Korra herself certainly counts as well. Tenzin and Tonraq may have intended to have her trained as The Chosen One from early childhood for her own protection rather than as a means by which to turn her into a tool to use for personal gain, but the end result was effectively identical. Korra's own temperamental affinity for violence probably had something to do with it, but either way the result wasn't pretty — she grew into a perfect weapon who believed she had no value outside of her powers and responsibilities, and she essentially failed to mature emotionally and spiritually past the age of four as a result (with sometimes terrifying consequences). Korra's character arc in Books One and Two essentially involves her figuring out how to defuse herself and exist as her own person outside of her predetermined role (and even then, she can be pretty ruthless for a good guy!).
Transformers Animated: Ultra Magnus reveals the goal of Project Omega is to create 12 super-weapons with reduced intelligence so they would never question that their purpose in life is to destroy or kill. Ratchet is horrified at it, while Ultra Magnus justifies it with the Decepticon threat getting worse (several Con victories had planets destroyed). At the end of the war, only one is still active (one is in stasis, and the another is missing) with all the others dead. In the present Cybertron is thriving and at peace, while Ratchet questions if what they did to achieve that peace was right.
The Hitler Youth, trained and indoctrinated from around 10 years of age. Attendance was mandatory, and the program produced such extremists as the ones found in Orwell's 1984 that reported their own parents for "subversive" behavior. Children found in conquered territories that resembled their Aryan ideal were kidnapped and forced in the Lebensborn, who "adopted" said children into Nazi Germany.
An English king (probably Edward III) is quoted as having said, "To train a longbowman, start with his grandfather."
Edward III was also a Tyke Bomb himself, forced to fight for the father he hated at the age of twelve, crowned by rebels at the age of fifteen. When he was eighteen, he dismissed the courtiers who had done this to him with extreme prejudice.
English archers qualify for this. During the Hundred Years War, each English village had to train its young men in archery. You started at around six or seven. Ten years later, you would have a enormous muscles in your upper body (so much so that peoples bone structures actually warped), your own longbow (which only other archers were strong enough to draw), a scary reputation and a leader to fight for.
The Khmer Rouge of Cambodia apparently used real-life Tyke Bombs as their enforcers. They made them torture and kill small animals starting at a very young age, and gradually moved them up to dealing out pain to people. By the time they were twelve or so, they could execute a starving peasant as if they were squashing a fly, and obeyed the commands of Khmer Rouge cadres like trained dogs.
Taken to disturbingly literal ends by various terrorist groups and less moralistic militias, who are often known to use them as suicide bombers (the Islamists are the most infamous for it today, but the LTTE and some of the less sane Basque and various political undergrounds have been known to use them).
The Viet Cong were infamous for this practice in the Vietnam War, such that US soldiers were ordered to shoot any kids approaching their positions. Subsequently this was one of the origins of the "Baby Killer" insult.
During Moor occupation of Spain and Portugal a large number of the sultan's top soldiers were the saqalibas, East European men kidnapped as children during occupations and invasions of their lands and raised as devoted and effective soldiers. They were educated in The Spartan Way, didn't live in misery, and were destined to important military charges. They became a lobby with whom the pretenders to the throne had better be on good terms.
And speaking of The Spartan Way: All male citizens of ancient Sparta were trained as warriors starting at age 7. From then until they reached full adulthood, they lived only with other Spartan warriors and warriors-in-training.
This goes for the Ottoman Sultan's Janissary corps as well, typically conscripts from Greek or Bulgarian Christian families who were taken during adolescence, circumcised, converted to Islam and given elite combat training. Because the Sultan's mother was invariably a member of the previous Sultan's harem, the Sultan was considered "half slave" and the Janissaries received their pay from him personally.
Interestingly, since the Sultan wanted to avoid having an aristocratic class that would undermine his power, he picked all his high-ranking officials and governors from these children as well. No wonder that during bad times people were sometimes actively trying to get their children picked.
Ironically, the Janissaries themselves ended up becoming the aristocratic class they were meant to prevent. After a couple hundred years of kingmaking, finally, one slightly more Genre Savvy Sultan than his predecessors attempted to stop the decline that the entrenched Janissary elite was perpetuating to protect their privileges. Unfortunately, this was in the 19th century, by which time the Ottoman Empire had declined greatly and become the plaything of their neighbors.