The entire plot of the appropriately named Reprisal is Rasalom's revenge on Bill for almost causing Carol to have a miscarriage when she was pregnant with him by refusing to have an affair with her. The goodness of him refusing to break his vows as a priest did this, so it wasn't like Bill almost killed him on purpose. Rasalom responds by ruining Bill's life, mostly by committing horrible atrocities on the people close to him. Rasalom seems to do this a lot.
Done a great deal in Aesop's Fables. One particularly harsh example is in the story of the monkey and the camel. The monkey danced for all the desert animals and amused them with how nimble and cute he was. The camel saw this and figured that he could do just as well. He showed off, trying to dance as well, but was much clumsier and oafish. The animals were so annoyed at his terrible dancing that they drove him out of the desert, and then ate him, "serving refreshments of camel humps and ribs".
In the first Alex Rider book, Herod Sayle planned to kill millions of innocent schoolchildren as revenge for the Prime Minister bullying him at school. Then we have Damian Cray in the fourth book, who arranged the death of a journalist who objected to the violence in his video games, and later told Alex he planned to kill him before he found out he was a spy, on the basis that Alex had done too well at what was supposed to be an extremely difficult game. And then in Scorpia Rising we have Razim, who, as a child, stabbed his nanny in the leg when she told him off for teasing his sister. Yeah, Anthony Horowitz is fond of this trope.
In Altered Carbon, TakeshiKovacs is placed into a torture program for 24 simulated hours by some Punch Clock Villain technicians hired by the Big Bad. After he escapes, he remembers a passage from his favorite author about making every struggle personal. He returns to the technicians' office and kills everyone who works there, then goes to a strip club that is tangentially related to the affair and massacres everyone working there as well. He melts the heads of everyone he kills, preventing them from being resurrected in a new body, as most people are after death. His rampage is considered outrageous by everyone who learns about it.
In A Nightmare on Elm Street: Perchance To Dream, main character Jacob Johnson uses his powers to stop everyone in Springwood from dreaming in order to protect them from Freddy. This has the adverse side-effect of making everyone edgy, paranoid, and violent; at one point a character browses through a newspaper and finds a section mentioning a kid who stabbed his teacher in the eye with a pencil after getting a bad mark and a man who shot his wife because she was "vacuuming in a really irritating way".
Not as violent or as graphic as some examples, but Anne does this in the Anne of Green Gables series in one of the most infamous scenes in all of literature. Most of the girls of Avonlea school are quite used to being teased by Gilbert Blythe, and most ignore it or become mildly offended. When Gilbert dares to make fun of Anne's red hair, Anne smashes her slate over his head and breaks it in half. And refuses to speak to him for years afterward. Quite the hefty punishment for one ill-timed comment.
One of the first things we learn about Gregor Clegane is that he held his little brother's face to a burning brazier for playing with one of his old toys, scarring him for life.
Petyr Baelish's kingdom-conquering is mostly due to a grudge he nurses from being rejected by his childhood sweetheart for a wealthier and more dashing man.
Tywin Lannister is well known for his harsh retribution. A popular song, "The Rains of Castamere" was written about how he completely wiped out two noble houses for being disloyal.
The Freys have possibly the most shocking example: After Robb Stark reneges on his wedding promise to House Frey, Lord Walder massacres Robb, his mother, most of his noble bannermen, and most of his army at the wedding feast of his uncle, thereafter called The Red Wedding.
Joffrey Baratheon/Lannister is also know for this trope, typically cutting everybody's heads off for any act of defiance or making them duel to the death. However, one of his biggest moments of douchery comes when he has Sansa Stark stripped naked and beaten bloody, in front of the entire court, because her brother won a battle.
Even though it's not direct retribution for what he's done, the torture Theon goes through at the hands of Ramsay is much harsher than the more honourable punishments the reader may expect he'd get.
The punishments in Candide are wildly disproportionate, and are Played for Laughs. To name a few, one character is given several thousand lashes for taking a walk, another character is hanged for expressing his beliefs (and for fun), the latter's companion is lashed for simply being his companion, etc. The book is filled to the brim with this sort of thing.
In Mikhail Akhmanov and Christopher Nicholas Gilmore's novel Captain French, or the Quest for Paradise, the titular character retells the story of Captain Regos to his new wife. Regos, a space trader like French, once traveled with his beautiful wife to a planet ruled by a tyrannical dictator who fancies himself God Emperor. While most planets treat space traders like royalty (or, at least, honored guests), the dictator took a liking to Regos's wife, had his people tie Regos up and send him back to his ship. However, Regos's wife refused to pleasure the dictator and was executed the next morning for displeasing the God Emperor. All Regos got were her ashes. Regos spends the next several months in the system's asteroid belt building a giant laser cannon, which he then uses to threaten the planetary population to turn over the God Emperor to him lest they all pay the price. Finally, someone does get smart and hand over the dictator. Regos proceeds to torture him for many days, recording the "sessions" on video before finally killing him. The video has since been distributed to all worlds with a clear non-verbal message - don't fuck with space traders. When French's wife asks him what he would do if something similar happened to her, he replies he'd build an even bigger laser.
In The Lotus Eaters, Legate Pigna gets wadded up paper thrown in his face and yelled at by Carrera, who was angry about how bureaucratized the Legion was getting in the year after his Heroic BSOD. The response? Plot with the enemy to overthrow the government.
Arguably, Carrera's nuking the city to get at the family of the terrorist organization's leader also qualifies, considering earlier in Carnifex it was shown that his people could get at the family members with more selective means of killing.
In Carrie, the protagonist's mother, Margaret White, once caught her asking a sunbathing neighbor about her breasts when she was three. Her reaction was to try to kill her with a butcher knife.
In Edgar Allan Poe's The Cask of Amontillado, the narrator, Montressor, is insulted by Fortunato prior to the beginning of the story. While it isn't said what the insult is, apparently it wasn't so severe that Fortunato thought their friendship was dissolved. In any case, it's difficult to imagine that he could have done anything that would make walling him up in a wine cellar and leaving him to die of dehydration anything but disproportionate.
In The Highland Twins at the Chalet School, when Fiona McDonald makes a snarky comment at Betty Wynne-Davies, Betty responds by planning to steal the Chart of Erisay, a document containing military information about the remote Scottish island where the McDonalds live. She then makes a deal with a Nazi spy to hand it over to him, after he hears her talking about it and corners her. When news gets back to the school and police are called in, Betty winds up being expelled.
More generally, one way to guarantee getting punished in the Chalet School, usually by fines and a heavy ticking off, is...talking slang. Yeah.
The Thrall district monorail breaks down one day in Clocks that Don't Tick. Despite it taking the workers only a matter of minutes to repair it, one of the Bosses had the head engineer dragged away and locked in an empty warehouse to starve to death, a Thrall's worst fear.
In Freedom, Loki/Gragg ruins the credit rating of someone fool enough to cut his queue.
In Digital Devil Story, the entire plot is set in motion because the Alpha Bitch Kyoko was rejected by our protagonist Nakajima. She dupes Jerk Jock Kondo into beating the crap out of Nakajima. Thoroughly displeased, Nakajima summons the great demon Loki and has the demon consume Kyoko's and Kondo's souls.
In one Brothers Grimm fairy tale, The Dog and the Sparrow, a wine-carrier drives over a dog sleeping in the middle of the road and kills him. The sparrow, who had befriended the dog earlier, decides to get her revenge by: pecking holes in his wine barrels until the wine runs out, pecking out the eyes of his horses and causing them to crash (or in some versions, tricking the carrier into killing them with his hatchet), summoning all the birds in the world to eat the corn stored in his house, tricking him into destroying his house with his hatchet when he tries to kill her, and finally causing his end by getting him to kill himself with the hatchet.
Lady Holdless Thella of Renegades of Pern lives and breathes this trope. In one case, she and her raiders ambush a trading caravan, destroying several carts and killing or wounding most of the traders and their beasts. She does this because earlier, when she was chasing down a family running from her, she encountered the traders, and the man she questioned was evasive and unhelpful. Even her origin smacks of this. She became the self-styled "Lady Holdless," scourge of the countryside, because she wasn't in the line of succession (passed from father to son).
In Laurence Yep'sDragon Series, a teenager is forced into a marriage with a river spirit. Upon escaping (after a thousand years), and seeing her former village had become a wealthy and industrialized city, Civet is overcome by loss and decides that dragons are responsible. She destroys the Inland Sea where the Inland dragons live, by taking away all the water, and then uses the water to destroy River Glen, her former village.
In the period mystery Eater of Souls, an ancient Egyptian serial killer murders people who'd subjected him to extremely minor offenses, like buying the company of a tavern prostitute before he could cross a room to purchase her services himself.
In Alethea Kontis's Enchanted, Sunday's brother Jack was turned into a dog for killing the prince's dog. Later, the prince remembers what had happened. Jack had pushed the dog away with his foot, which should not have killed, and would not have killed any other dog in the court. So the prince's Fairy Godmother turned him into a dog. Whereupon Jack's fairy godmother appeared, limited it to a year, and then decreed that the prince — who had done nothing — would be turned into a frog for a year to teach him humility, or something.
Achilles from the Ender's Shadow series takes this to an extreme by killing people for doing good things to help him because he can't bear for anyone to have seen him helpless (and he has a fairly major inferiority complex, so his definition of "helpless" is very loose).
In the Farsala Trilogy, a young smith named Kavi loses the use of his hand when a deghan tries to grab a sword from him. Years later, he betrays Farsala to the Hrum and causes the death of the entire deghan class.
In one G. K. ChestertonFather Brown story, the Asshole Victim was inclined to do this. In retaliation for an insult years before, he threw a Moslem into a pig-sty, breaking his arm and his leg, and then left him there overnight. That wasn't why he was murdered, though: He proposed to his ward, and was rejected. His planned revenge for this was to have her marry an old friend of his, and then have the old friend hanged for murder.
One villain in the Fingerprints series got her Start of Darkness when she vowed revenge on the person who murdered her mother. Upon learning that the murderer had already died for unrelated reasons, she decided that wasn't satisfactory - someone had to suffer, and it didn't particularly matter who. She began targeting the hero (who was related to the murderer but didn't even know about the murder, let alone take part in it). Unusually, the villain is eventually persuaded by the hero that what she's doing is pointless... but only because she finds another target more directly connected to her mother's murder, whom she proceeds to go after with great enthusiasm.
The Grandmother in Flowers in the Attic punishes the children severely for the most minor infractions, including simply existing as the products of incest.
In Ray Bradbury's short story The Flying Machine, a Chinese emperor beheads the bewildered inventor of the titular machine, has the machine burned along with the inventor's remains, and has the ashes buried secretly, all because someone might be inspired to use such a machine to destroy the Great Wall of China.
A minor character in Galaxy of Fear is trying to get to an Escape Pod before the ship he's on self destructs. Two kids, Tash and Zak Arranda, who'd been on a pod leave it to help someone, then try to get back on, but the man thinks they're cutting in front of him. What does he do? Lock them in a storage closet, leaving them to die. The ship does not actually explode, it was a false alarm, but that's harsh.
The Lies of Locke Lamora and its sequel feature a powerful magic guild called the Bondsmagi. One of them, Falconer, seem to be particularly guilty of this trope, as he tortures the main hero and threatens him with death of his friends just for speaking to him with no respect.
The Bondsmagi love disproportionate revenge. The reason everybody respects them is because killing one will get the entire guild after you to kill you, your family, your pets, etc. They're also known for burning a city to ash because a dozen of them died during a war against the Therin Empire.
In Victoria Forester's The Girl Who Could Fly, Conrad is forced to give up his science project for the one his teacher selected. So he destroys Bella's, because she's happy and her parents love her.
In the Gone series. In Fear Cigar kills a fellow fisherman in a drunken brawl. Since he committed murder, Caine sentences him to Penny for a day. 30 minutes was enough to cause a two-day state of shock in the previous victim. Even Caine is horrified at the end result.
Also in Fear, Caine asks Penny to leave Perdido Beach after the backlash from what she did to Cigar. So she drugs him, traps his hands in a cement block, and staples an aluminum crown to his head.
A race introduced by Timothy Zahn in the Hand of Thrawn duology have this as part of their legal code. The penalty for murder is death, life for life - either one who is guilty, or ten of his clan who are innocent. They use this to justify flattening a Bothan space station and further inflaming the political mess engulfing the New Republic.
The bothans themselves. A species had a single member slight the bothan race, and in retaliation, they burned the homeworld, slaughtered every member of the species, erased records of them, and Made them never have existed.
Dolores Umbridge forces students to write lines in their own blood with a quill that cuts into the skin on the backs of their hands. It's stated that at least one student's hand is bleeding quite badly, and that Harry himself has another permanent scar. All of this for speaking out of turn and/or questioning the Ministry.
There's also the treatment Harry received from the Dursleys for most of the eleven years prior to his acceptance into Hogwarts, and occasionally afterward as well. He was confined to the cupboard under the stairs just for existing, yelled at for asking questions or innocently mentioning strange dreams, and punished (up to and including being denied meals) for exhibiting signs of the hated magic, which he neither understood nor was able to control. For example, in the first book he gets locked in the cupboard for much of the summer just for talking to a snake after the "vanishing glass" incident.
Voldemort once applied for the position of Defense Against the Dark Arts teacher at Hogwarts though his primary goal was to hide the Ravenclaw diadem Horcrux in the Room of Requirement. Dumbledore rejected his application because he knew Voldemort had ulterior motives for being there and he wanted him gone. That and he figured a snake-like Humanoid Abomination that reeked of Dark magic probably wouldn't be a good influence on students. Even though he had accomplished his real goal, Voldemort still felt pissed off by the rejection. And that's why no Defense Against the Dark Arts teacher has ever managed to hold on to the position for more than a year after Voldemort's visit. Turns out the position really is jinxed.
Word of God later stated that while Voldemort's death lifted the curse, Slytherin's shady reputation nonetheless stands.
While Argus Filch has a case of Strawman Has a Point about the messes caused by the students as he's a Muggle Born of Mages, his idea of how they should be punished for it is not. His desired methods so line up with Dolores Umbridge, that he was the only one on her side as it meant he could use a horsewhip on rule-breakers.
Also, Draco Malfoy keeps bullying Harry and his friends just because Harry didn't accept his offer of friendship (even after Draco insults Ron in the process). What a kid!
In Holes, every member of the Yelnats family and their descendants are cursed with bad luck because one of their ancestors, Elya Yelnats, forgot to fulfill a promise to Madame Zeroni. The promise? All he had to do was carry her up a mountain, and sing a certain song while she drank from the spring on the top.
Admittedly, the spring apparently had some sort of healing/growth properties that would have given the old and possibly dying Zeroni a longer life. Still a bit harsh, though.
She did give him fair warning when the made his deal. If she didn't follow through, what good was the threat? It's also a very mild curse — just bad luck, and usually non fatal. Stanley Yelnats the first was robbed by Kate Barlow and left in the desert to die but he still survived.
After he carried her descendant up a mountain and sung the song to him while he drank from the water at the top, thus fulfilling the promise and causing good luck.
In Death: A number of murderers and criminals throughout the series have done this. Promises In Death reveals that Max Ricker sliced up three men and left them floating down a river. Why? Because they stole from a store owned by his son, Alex Ricker, and caused him embarrassment. Creepy!
The protagonist of Larry Niven and Jerry Pournelle's Inferno believes that being sent to Hell for eternity is Disproportionate Retribution for finite sin (not exactly a new idea - see Religion and Mythology section). He later comes to the conclusion that punishment in Hell is a) not eternal, and b) actually a form of highly extreme psychotherapy.
Niven's short story from his Known Space series, "the Jigsaw Man", involves harvesting transplant organs from people condemned for capital crimes. Given the ever-increasing demand for such organs, the definition of "capital crime" gets broader and broader, with our protagonist facing execution for traffic violations.
In I Want My Hat Back the Bear loses his hat and eventually learns it was stolen and that the thief lied about seeing his hat. He eats the thief and lies about it when questioned.
Roughly two thirds of The Sum of All Fears is about Elizabeth Elliot trying to ruin Ryan's career and marriage for taking offense to her bad manners in the previous book.
The Judgment, the short story written by Franz Kafka, has a man's father reveal that he is aware that the son has been lying to an old friend living in Russia (who may or may not exist) about his engagement. The father then orders the son to drown himself. The son does so.
In the Warrior Cats series, Ashfur gets dumped by Squirrelflight in favor of Brambleclaw. What does he do? He tries to murder her father, the Clan's leader, and get Brambleclaw blamed for it; when that fails, he waits moons until he has the chance to try again, this time targeting her kits. All because she picked his best friend instead of him.
Long before that, Thistleclaw ordered his apprentice to attack and almost kill a kit who had accidently wandered into their territory.
Don't forget Scourge having Violet nearly beaten to death because she dared to look for her missing brother.
In Rudyard Kipling's Just So Stories, the Cat who Walks By Himself gets some pretty harsh treatment simply for saying his Catch Phrase "I am the Cat who walks by himself, and all places are alike to me." Some of the harsh treatment may be justified, because over a large part of the story, the Cat is clearly trying to get something without giving anything back in return — nevertheless, when the Dog and the Man lay down the law and tell what they expect of the Cat in the future (keep the mice away, be kind to babies) and the Cat agrees to their terms, they still vow that they and their descendants will torment the Cat for always and always just because he spoke out of turn.
Earlier on in the story, the Dog immediately tells the Cat that they can never be friends again just because the Cat didn't want to come along on his exploration trip. Really, it's not all that hard to see why the Cat would prefer not to retain too close a relationship with such jerks.
The Dean Koontz short story "Kittens". Sure, it's horrible when you're a first-grade girl and you find out that your father has been drowning your cat's litters of kittens and claiming that "God took them", but drowning your twin baby brothers in the bathtub to get back at him is going a little far. (Especially disproportionate because drowning kittens was a common practice back in the day.)
The captain of the Albatross in the Knight and Rogue Series has Michael flogged for accidentally spilling paint on him. Bonus points for Michael not having been the one to spill the paint in the first place.
In Les Misérables, Jean Valjean originally set out to steal a loaf of bread to feed his hungry family. However this was armed breaking-and-entering, and due to draconian laws and a series of escape attempts, he wound up serving 19 years in the galleys; and then, unable to find work or shelter after his release, he reoffended (stealing a 40-sous coin) and was given a life sentence.
In Sergey Lukyanenko's Line of Delirium (inspired by Master of Orion), the backstory has humans wiping out the entire Sakkra race after they invade three remote human colonies (they can't control their reproduction and need space). The Emperor justifies this by claiming that the Sakkra uncontrolled birthrate would eventually result in them being a threat to everyone. The other alien races still haven't forgiven humans for the genocide.
Also, the sequel reveals that an attempt by a human colony to secede resulted in every colonist being slaughtered by a militia from other worlds. The protagonist took part in the slaughter.
In Rosemary Well's picture book version of The Little Lame Prince, the kingdom is under the influence of an evil usurper, and the crown prince is taken in by a convict who was "condemned to death for stealing apples".
In the MTG set novels of Kamigawa, this is a big part of the Hyozan oath. The actual wording of the magical contract promises tenfold vengeance, but this is just a bare minimum. When Kobo is murdered, Hidetsugo's vengeace includes condemning the actual triggerman to an eternity of unbearble agony destroying Minomo academy, exterminating the moonfolk, and then eating their god. he also said some very mean things
In Diana Wynne Jones's The Merlin Conspiracy, due to some inadvertent time hopping as he flees an assassin sent by two big bads who want him dead for no discernible reason, Nick winds up in the assassin's home before the hit was taken up. A little over a decade, in fact. The two big bads pay a visit as the children they were, and Nick laughs as one steps on an egg, which sets off the two's berserk button and triggers the need for revenge years later.
During the same interlude, Nick hangs up on the assassin's ex-wife in the middle of a phone call, which sets in motion her ultimate plot to take over Britain and destroy its other magic-users before they could oppose her. Without which the rest of the book probably wouldn't have happened anyway.
Angels are expected to dedicate their entire lives to serving the Judeo-Christian God. Failure to do so will result in having ones wings ripped off, their magic stripped away, and they will be exiled. If they ever manage to regrow their wings or use magic again, they are accused of devil-worship and executed.
They're also known to punish unauthorized/unapproved sex by superglueing the participants' cloacas (the avian orifice for sex, excretion, and defecation) shut. This often leads to a slow, painful death as the body is no longer capable of removing waste.
In Robert E. Howard's Conan the Barbarian story "The Phoenix on the Sword", Thoth-Amon, having gotten back his Ring of Power and wanting more than anything to make his former master Ascalante pay for all the humiliation he's heaped upon him, sends a demon of Set after him and throws in, just for giggles, everyone with him at the time. Including, as it happens, Conan whom Ascalante was trying to assassinate at the time.
In "Beyond the Black River", Conan vows to kill ten Picts for Balthus's death, and seven for the dog that died with him. To be sure, the Picts had slaughtered a lot more than seventeen in their attack.
In Terrier, a slum-dweller thinks the neighbors are puttin' on airs with their one nice thing that they own (a necklace or an antique book, things like that). Response? Ransom and murder their children as the Shadow Snake!
One of the minds behind the counterfeitting plot in Bloodhoundwanted revenge for a dishonorable discharge after he'd spent years as a loyal soldier—he only hit his officer because he was The Neidermeyer. Clearly the best response is to overturn the country's entire economy.
In Mastiff, the mages don't like the King's proposed tax on them. So they abduct one of the child princes with plans to kill him, kill dozens of others along the way, and plot to overthrow the government.
In the Battle Magic by the above author, The Emperor of the Yanjing Empire is shown to be prone to this. He has a rose garden and the gardeners working on it burned just because a small patch of mold was found on one plant when he was showing it off to Briar and Rosethorn. The rose bush that had the mold escaped being burned because Rosethorn begged the emperor to give it to her as a present after she had healed it.
In the very first Rainbow Magic series, Jack Frost captures the Rainbow Fairies because he wasn't invited to a party—even after he was told he could stay and have fun once he showed up to crash it. He goes on to do this many, many more times.
Slagar the Cruel from the Redwall novel Mattimeo arguably qualifies, since his entire reason for being is revenge against Matthias for his grievous, insanity-inflicting injuries...that were actually well-deserved, what with him being Always Chaotic Evil and all, and furthermore had nothing to do with Matthias whatsoever. Simple logic doesn't stop him from kidnapping Matthias' son (the eponymous Mattimeo) and several other children, however, as well as siding with the delusional polecat-slash-pagan deity Malkariss.
The Redwaller kids point out immediately afterwards that Asmodeus's poison corrupted his mind and made him go batshit crazy into thinking that the Redwallers were responsible, even though he decided to steal everything valuable in the abbey after they'd saved him from death.
One of Gabool's pirates, was complaining that they don't get enough shares of the loot. Gabool agrees and allows him to take any treasure he wants, insisting he take that one crown. After the minion puts the crown on his head, Gabool instantly decapitates him as a warning to anyone else.
Speaking of pirates, when Vilu Daskar caught some members of his crew stealing, he had them savagely beaten and then hung from sunrise to sunset with saltwater thrown into their wounds for good measure.
Also Swartt Sixclaw found out that one of his minions may possibly be conspiring. He could simply just kill him, no. He orders him to feed a dead bird to another minion, beak, wings, skull, the whole thing. Once the other minion chokes to death, Swartt instantly accuses the first one of murder and orders him to be executed.
In Romance of the Three Kingdoms, Cao Cao responds to the death of his father at the hands of one of Tao Qian's officers by committing a genocide against Tao's subjects.
In an example of disproportionately low retribution, the head inquisitor in the Safehold novels gives orders that result in a massacre and is sentenced to one week's kitchen duty.
A lot of characters in Maggie Furey's Shadowleague trilogy teeter on the brink of this, but as of the first book (The Heart of Myrial), only one character has gone over - intending torture, rape and murder for a noble who seems perfectly unaware that her grunts (who have already died for their crimes) were committing said crimes, and killing whatever innocent bystanders stand in his way.
Mysterio in the Sinister Six Trilogy spent a year driving Brick Johnson insane, culminating in making him commit suicide. He then proceeded to crash the funeral and tried to kill everyone present. Why? Because Brick didn't help Mysterio get a job when they were in Hollywood.
Sisterhood Series by Fern Michaels: Okay, some of the punishments the Vigilantes subject the villains to can be considered this. A notable instance is the book Vendetta in which the Vigilantes skin John Chai alive! Well, the story says caning, but caning and skinning someone alive are not the same thing. His crime was drunkenly committing a hit-and-run on Myra Rutledge's daughter Barbara Rutledge, killing her and her unborn child, and then getting away with it because he's the son of the ambassador of China and used Diplomatic Impunity without a qualm. The reason the punishment in Vendetta can be considered this trope is because the crime occurred in Weekend Warriors, which is a few books back, and by then the reader will probably have forgotten the full impact of the crime.
In Slaughterhouse-Five a character speaks of feeding a dog steak and watch springs for biting him and proposes enacting horrible revenge on the main character for accidentally doing something involved with his friend's death! Now, this all happens offstage and the character's never seen again, so...
The decidedly anti-heroic protagonist of Stephen Fry's The Stars Tennis Balls has gone very off of the deep end by the climax of the book. Holding the Shadowy Secret Agent who exiled him to an island prison captive, he gives him a choice. To be shot dead, or to have the slenderest hope of survival by swallowing burning coals, in the manner of Portia in Julius Caesar. The poor agent manages - somehow - to choke down a coal or two, and we have the horrific description of huge blisters erupting around his mouth as his vocal chords and windpipe are burnt out. This proves too much even for the protagonist, who promptly "mercy-kills" the guy with a shot to the head.
In Storming Heaven by Dale Brown, a plot point in the backstory is how meddling bureaucrats put an end to a border patrol program because a pregnant drug mule carrying contraband in her body panicked after a prolonged chase by helicopters and was induced into premature labor- the drugs in her body killing both herself and her baby, resulting in horrible publicity for the program. Again, they were chasing drug mules with helicopters.
Grzylov from Air Battle Force loses a baseful of bombers when Patrick has them destroyed to stop them attacking Turkmenistan. His response in Plan of Attack? Nuclear sneak attacks that wipe out most of the American strategic arsenal.
In Executive Intent, Somali pirates attack a Chinese ship. At first, the Chinese helicopter sent tries to warn them off. When the pirates start killing hostages, the helicopter crew respond by attacking the pirates. Fair enough. Then the helicopter is shot down by a pirate. The Chinese response is a massive aerial and amphibious attack and takeover of Mogadishu. Later, some Yemeni terrorists crash an explosive-laden boat into a Chinese warship, sinking it. The Chinese proceed to punish Yemen too.
The Sword of Truth series sees a man being tortured by a Mord-Sith after he assassinates a mage in the opposing army (after stabbing a little girl; the girl survives, the mage doesn't). Surprisingly, the torturers are the heroes. After the man has spilled all his information, the mage's lover orders him to be tortured to death as slowly as possible, in retaliation for being so cocky when he was captured.
In the first book, the staff taking care of the tomb of Darken Rahl's father were executed if a single petal fell off the flowers there or a single torch went out in Rahl's presence. And he considered himself merciful for allowing them a quick death in such cases.
In one book, Kahlan looks through old records of trials, one of which includes an entry about a wizard who had been executed for being an incurable alcoholic. Her initial response is to think it's an example of this trope, but when she thinks about it, she realizes that, given the raw destructive power of wizards, it just wouldn't be safe to let the guy live.
In Poul Anderson's "Time Lag", the invaders make an example of a number of villages when they are faced with opposition.
Michael Crichton's Timeline has Robert Doniger, the business-man who sends the heroes back in time to the Middle Ages to fix something gone wrong. Long story short, lots of things go wrong. When our heroes do get back, they get their revenge on Doniger, unethical as he is, by sending him back in time with the same machine to the Middle Ages where he gets a nasty case of the Black Plague.
Doninger wanting to leave them in the past to save his company's rep happened in the book as well. He says he's kidding, but the other character, who knows him very well, doesn't believe him. Also, there's the part about him wanting to sell time travel tech to rewrite history, so Doninger comes across as deserving what he gets.
In To Kill a Mockingbird When Atticus Finch embarasses Bob Ewell at the trial, Bob Ewell takes revenge by trying to murder Atticus's children.
Twilight: Wordof God says Lauren fell prey to a modeling scam that cost her over a thousand dollars and a good chunk of her hair. What made her deserving of this? She made one relatively minor sarcastic comment about Bella.
In Unwind, the process of Unwinding is basically having every single part of a person's body dismembered and harvested to be used for transplants simply because they were a difficult teenager or the parents couldn't afford to take care of them. And every sngle one of these people are between the ages of 13 and 18.
In the Watersong novels by Amanda Hocking, Persephone's four handmaidens goofed off and weren't there to prevent her rape and murder at the hands of Hades. Persephone's mother, Demeter, was understandably angry at four human girls for not being there to fight a god off, and turned them into sirens. It turns out to be a case of Cursed with Awesome, since they don't mind so much having to eat the hearts of men, though Demeter gives some explanation of how eternity without love is the punishment. Two of the original sirens are killed by the leader, and the main character replaces one of them since there must always be four. In the name of continuing to punish the two remaining, Demeter refuses to help the MC, and doesn't much care about the thousands upon thousands who are suffering and dying at the hands of the sirens.
Nearly the entire class on the 30th floor in Wayside School fell victim to this trope courtesy of Mrs. Gorf, who would turn her entire class into apples for minor offenses such as sneezing, saying "God bless you" after said sneeze, crying, and arriving late for class.
Also, Mrs. Drazil. If you move away, but don't hand in your final homework assignment, she will hunt you down for the rest of your life.
In Andy Hoare's White Scars novel Hunt for Voldorius, Malya is chosen for Voldorius's equerry. They get her to obey by threatening to kill a hundred people every time she is disobedient.
In the Conan the Barbarian story "Wolves beyond the Border", the Pict shaman Zogar Sag is briefly jailed for mugging a merchant and stealing his liquors. He react by summoning a Swamp Devil (actually his brother) and sending him to kill the merchant and the guards who arrested him. However, Conan stated that imprisoning a Pict is the worst offense you can make to him.
According to Aristotle, Greek Tragedy actually requires that the Tragic Hero suffer disproportionate retribution for his actions. Aristotle judged that it had to be this way because if the hero was innocent than he wouldn't get Character Development and if he deserved his fate than it wouldn't be tragic.
This is a recurring theme in Roald Dahl's books. Villains often suffer horrible punishments (often death) for their crimes, even if the crimes don't warrant it. (A lot of them are the type that Would Hurt a Child, but even so, what happens to a few of them is rather grim.)
What happens to most of the kids in Charlie and the Chocolate Factory qualifies. Their punishments were brought on by their flaws, but still rather excessive. Even though they all live and recover to some extent they have some unpleasant permanent changes. Violet, for example, is no longer inflated, but is still blue. Just for chewing gum.
This is due to him as a child being sent to an sadist boarding school where the teachers beat him constantly. So almost always his books involve kids triumphing over evil adults.
In The Burden of Evil by Strugatsky Brothers, a colony of hippies (called "flora" in text) is attacked by people of the town Tashlinsk, and its inhabitants beaten and arrested, simply because a few of them stole food in the town. A kind schoolteacher trying to stop the mayhem is killed.
In-Universe we once get a painting named "Das Motorrad unter dem Fenster am Sonntagmorgen" ("A motobike under the window on Sunday morning"). The painting shows a a bedroom, in which a man in a nightgown runs towards the window, grenade in hand. The implication is that the motorbike woke the man up, and for this the man is going to blow up the bike along with the motorist. the artist turns out to be Adolf Hitler
The Windwater Pack Zephyr’s reaction when he encounters the coyote that killed his pups is to shred him quite literally. The only thing that saves the coyote's mate is that killing her would leave their son an orphan, like Zephyr himself
This is part of the main plot to Misery. Annie rescues Paul, who she's a big fan of, but then becomes furious when she buys his latest book and finds out that he killed off her favorite character. Annie then threatens to kill Paul unless he writes a sequel to the book where the character is brought back to life. Many of the tortures Paul goes through fit this trope as well. Annie refuses to give Paul his painkillers for days and when she finally gives them to him, she forces him to wash them down with soapy water, all because she didn't like that he had swearing in the new book he was working on. Also, when Paul complains that one of the keys on his typewriter doesn't work, Annie cuts off his thumb with an electric knife.