A rather horrifying example appears in Akame ga Kill! when Kurome, the evil little sister of the titular Akame, finds out that Night Raid's newest member, Chelsea, murdered her (Kurome's) comrade, Bols. Chelsea attempts to assassinate her, but she botches the attempt and tries to run for it. Unfortunately, when Kurome realizes that Bols must be dead, she reveals the most sadistic part of her personality and sends her people puppets, Natala and Doya, after Chelsea. What happens to Chelsea is hard to watch. Doya shoots her fingers off her left hand with a gun. Then Natala severs her right arm. Then Doya fatally shoots Chelsea in the back. Then Natala chops Chelsea's head off and hacks her to pieces. Afterwards, what remains of Chelsea is dissected for information and fed to Seryu's "pet," Koro. Chelsea's head is the only thing left of her, and they stick it on a pike in the middle of the town of Romary. Kurome's rage is understandable, given Bols was a devoted family man, but the sadism apparent in this scene shows just how monstrous of a person she is.
How does Nagisa's mother in Assassination Classroom respond to Koro-sensei trying to tell her how to raise her son? She tries to burn the Class 3-E building to the ground!
The King of Midland in Berserk seems like a pretty mild, decent guy...until he discovers that Golden Boy Griffith slept with his daughter the previous night. After Griffith correctly deduces that the King was lusting for his own daughter (in which case Griffith beat him to her virginity), he has Griffith locked in the deepest level of the worst dungeon in Midland and put to the torture by the most sadistic little freak in the world, while also having Griffith's mercenary army, the Band of the Hawk, declared outlaw, butchered and hunted endlessly. Overreaction much?
Ironically, the King's awful punishment towards Griffith could be justified from a lawful perspective if one takes into account Griffith's other treasonous crimes against the Kingdom of Midland, like say... arranging for the murders of the King's brother, nephew, second queen, and a handful of nobles. But since no one ever found out who were truly behind these acts and the King didn't seem to particularly care about these individuals anyway, those plotlines get dropped after the fact and are never once mentioned in relation to Griffith's punishment.
And then, after Guts returns and the Hawks regroup and rescue their former leader, the King decides to send in the Black Dog Knights, the worst rapists, murderers, and all-around scum Midland has to offer, led by a truly nasty piece of work of an Apostle, in order to kill them all.
In Bleach, Aizen pays more attention to his captive Orihime than to his biggest fangirls, Arrancar twins Lolly and Menoly. Their response? To get Orihime alone, and beat the shit out of her. When that fails (only on the fortunate timing of Grimmjow), their plan is to kill her while Ichigo is fighting Ulquiorra.
Another one would be Tousen. His closest friend was killed by her shinigami husband. So what does he want to do? Get rid of all the shinigami, all who have nothing to do with his friend's death.
The main reason for Tousen's revenge may have been that the Central 46 did not sentence to death the man that killed his best friend over something petty and so he wants to take down the entire Shinigami system through the most bloodless way possible: letting Aizen, a traitor, take over the throne to Soul Society.
Aiding Aizen's coup d'etat was somehow "the most bloodless" action possible? Even though Aizen intend to slaughter a whole town in the living world and harvest their souls to materialize a key that would unlock God's domain, in which Aizen would kill said God and forcibly take over? Riiiiight. One can only imagine the route Tousen would consider "bloody" by comparison.
While it's often overlooked because of the character's popularity as The Rival, Grimmjow's rivalry with Ichigo is insanely petty and mean-spirited. They are introduced when Grimmjow beats the unholy hell out of Ichigo until he can barely stand upright (purely to show up Ulquiorra, who Grimmjow dislikes), and Ichigo manages to get in a single counter-attack bad enough to scar Grimmjow's chest superficially. This insignificant injury combined with the fact that Ichigo's self-confidence irritates him is all the justification Grimmjow needs to go from picking on Ichigo to show up Ulquiorra to crusading against him with a hatred that borders on obsession.
Captive Hearts: Because a thief tried to rob the Kougamis centuries ago, his descendants were forced to serve the Kougamis for the next hundred generations.
The Political Correctness Gone Mad world of Centaur no Nayami runs on this. A seemingly innocuous comment (Like assuming someone has dyed hair) can be considered a hate crime. And result in the offender being arrested and sent to a reeducation facility.
Change 123 has Sora — who is using Kosukegawa to get Motoko mad so she can see her most powerful personality, Zero — chuck into a dumpster some Kamen Raider tapes that Kosukegawa gives her, tapes that are very important to him. Hibiki (the most abrasive of Motoko's normal personalities, all of who like Kosukegawa) sees this happen. Her response? Throwing a punch that makes Sora's bone stab out of her wrist. Ouch.
Lelouch has his moments in Code Geass. His response to Rolo murdering Shirley (Because she mentioned Nunnally, the one person Rolo wanted dead) is to wipe out the entire Geass Order. While there were undoubtedly some monsters in that number, he still has his minions slaughter kids. Tykebombs, yes, but kids.
The part where Charles kills his brother V.V. for lying to him for the second time seems like disproportionate retribution, even considering the pact they had, but doesn't seem so disproportionate once you find out what V.V. lied about the first time.
While Lelouch's reasons for taking out the Geass Order were indeed disproportionate, it's not like he wasn't going to do it eventually. Remember the Order's main goal was to research and weaponize Geass so they could control world affairs from the background (as demonstrated by Rolo's activities), which pretty much made them enemies of Lelouch from the get go (V.V.'s kidnapping of Nunnally and supporting Charles and Britannia notwithstanding). Besides, as noted, those kids were pretty much walking, breathing weapons anyway, so as cruel as it is to kill children, it wasn't like they were entirely unsanctioned. Especially if, again going by Rolo's example, the Order had those kids performing assassinations in their lower digits.
More of a villain-on-villain example, but in Deadman Wonderland, after Shiro breaks Genkaku's beloved electric guitar, the next time he meets her, he captures her and orders his men to cut her up and rape her. (Part of it was also because he seemed angry and jealous that she was Nagi's friend, but mostly because of his guitar.)
The entire point of Death Note is Light's belief that capital punishment (generally via heart attack) is the best way to rid the world of evil. His idea of evil people started out with understandable criteria like murderers and such, though he did have disturbingly vague plans of killing off other "useless" people as well. Once his acolyte Teru Mikami begins playing the trope completely straight by targeting lazy people, Light thinks that he has gone too far...because it is too early to be taking such steps. How much Light himself conforms to this trope is a matter of debate, but in several cases, boy does he.
The Lunatic Magician of Delicious in Dungeon, views all dungeon crawlers as thieves and deals with said adventurers either by feeding them to monsters or burning them alive. Note that most of these unfortunate folks have no idea any of the residents of the Golden Kingdom are even still alive. They just see it as collecting resources from a culture that died out long ago.
When Frieza's henchmen are trying out for the Ginyu Force, Captain Ginyu kills a Mook called Captain Strong because he is also a captain ("There's only one captain on the Ginyu Forces and that's me!"). He then kills another of Frieza's henchmen because he touched a Dragon Ball (which Ginyu forbade them to do), and does the same to the rest of the mooks trying out because they lack the style to be on the Ginyu Force.
Actually, the "only room for one captain" line is dub only. In the original? The guy's first-run tryout pose isn't quite up to snuff.
Dr. Gero wanted revenge against Goku for destroying the Red Ribbon Army. To that end, he created a series of androids that turned one timeline into Hell for twenty years and nearly destroyed the solar system in the main timeline. The Disproportionate Retribution comes into play when you considered that Gero's former boss, Commander Red, wanted the Dragon Balls and sacrifice numbers of his own men so he could become taller. Granted, Gero didn't know that, but it is still scary to consider that a petty goal of one minor villain caused so much trouble.
Broly from the eighth movie hates Goku with a murderous passion because shortly after they were both born, Goku's crying bothered him (and various terrible things happened shortly afterward, so he probably developed a Pavlovian reaction to the sound of Goku's voice).
It gets to the point where he so hates Goku, that he's willing to murder Goku's sons in his second movie because he thinks they're both Goku!
In Dragon Ball GT, a couple of teenagers call Vegeta a geezer while trying to flirt with his daughter. Vegeta ripped off their steering wheel and sent their car plummeting into the ocean. All things considered (given that Vegeta, in the past, has murdered people for less), they probably got off light.
Let's just face it, Vegeta's a recurring example of this trope. At the end of the DBZ series, at the tournament when a guy heckles him, he punches him in the face hard enough for him to forfeit the match.
Beerus does this a lot. Though he isn't precisely evil, he's very selfish and short-tempered, and has a tendency to destroy planets for the most petty of reasons. He argues that this is only natural: as the God of Destruction, destroying things is just what he does, and since he's a god, the lives of mortals are of little concern to him. The other gods of the series don't seem to share this outlook, but Beerus is so much more powerful than they are that nobody can really stop him.
In Battle Of Gods, he visits Earth, and says that he won't destroy it provided nothing annoys him. After Whis tells him about how good pudding is, he wants some. Buu wants all of the pudding to himself. So Beerus and Goku get in a fight with the fate of the entire planet resting in the balance.
Even more so, he revealed that he actually went to earth millions of years ago. He found Earth was full of Dinosaurs, they were a bunch of rude creatures so he wiped them all out.
In order to investigate whether or not Zamasu is actually Black Goku, Goku challenge him to a friendly sparring match in which he loses and takes it very badly. So how does Zamasu get back at Goku for this? He used the Super Dragon Balls to switch bodies with Goku, killed him and his family just to be a dick, he then went on to Future Trunks timeline, recruited Future Zamasu and killed all the gods there and destroys Future Trunks world just to specifically punish him for abusing the concept of time travelling. In other words, the entire reason why he wants to conduct his "Zero Mortal Plan" is because Goku defeated him in a sparring match.
In that same arc, Future Zeno erases the entire timeline's multiverse. This wasn't disproportionate in the anime, where Infinite Zamasu had become a spirit of dark energy that corrupted the entire multiverse beyond repair and threatened to reach out into other timelines, but it was in the manga, where Zamasu had instead split up into thousands of different clones that hadn't yet reached beyond Earth, something that Zeno could have easily erased seperately.
Aoba set his brother Izumii's room on fire so he could get in trouble for smoking and get beaten by their abusive father, just because he hit him a few times. Izumii, however, isn't completely innocent either, since the reason he hit Aoba was because he's under the delusion that he's The Unfavorite, but risking the possibility of burning their house down and subjecting him to child abuse just to get back at him seem like massive overkill.
A flashback in Elfen Lied reveals that Lucy killed Kouta's sister and father just because Kouta lied about his cousin's gender.
An odd example in ERASED. Airi tells Satoru that her father, after being accused of a crime (which he denied), was suspended and later fired from his job, divorced by his wife, and forced out of his home. His alleged crime? Stealing a chocolate bar from a convenience store. The odd part is that while the manga eventually subverts it, revealing that the real crime was far more serious and Airi had been lied to about the incident to protect her, the anime doesn't adapt that bit, and thus plays the trope almost ridiculously straight.
Excel Saga played this for laughs when Department of City Security head Dr. Kabapu forced his team to patrol the city in Sentai suits. Cue Stuff Blowing Up for minor offenses, like littering and flirting.
In Eyeshield 21, this is Hiruma's entire stance. To quote: "Attack attack and attack! Two eyes for an eye, two teeth for a tooth!" One wonders what sort of karmic retribution he's expecting for all the stuff that he does.
Minerva's father Jiemma is even worse, beating, publicly humiliating, and exiling members of his guild if they lose even one event or fight. ONE.
In Fist of the North Star, the villain Amiba decides to imprison Toki, get plastic surgery to look just like him, impersonate him, and perform horrible experiments on innocents to ruin his good name... because Toki slapped him in the face once. And not even deliberately, at that!
Hokuto Shinken, due to its horrific effects when it is used to kill, can often be seen as disproportionate for many of the bad guys that Kenshiro uses it on, particularly in Filler episodes where Kenshiro delivers a Cruel and Unusual Death to smalltime punks.
Mr. Heart really, reallyhates the sight of his own blood. If you make him bleed, even if it's just an accidentally-made tiny little scratch, you can expect yourself and everyone within arm's reach to die horribly.
Sōsuke Sagara of Full Metal Panic! breathes this Trope. Strangers who so much as looks at Kaname tend to wind up face-down, on the ground with a gun on the back of their heads, and Sagara preparing to "interrogate" them.
An example from the first episode of Fumoffu, when Kaname is kidnapped by some punks. Sōsuke tortures one of the gang members to find out who every single member of the gang loves the most.
Nakago from Fushigi Yuugi. The reason behind almost everything he does is because of this. He blames Kutoh for the death of his mother, only friend Tarlia (Seiran Den) and the sexual abuse he suffered as a child. He claims he 'wanted revenge on the Heavens that had given [him] hell.'
Also Suboshi. After Amiboshi dies, he blames the Suzaku warriors and to 'get his revenge' he kills Tamahome's family.
Gabriel the Fallen Angel and main protagonist of Gabriel DropOut, tries to use a horn that will bring about Armageddon, because a Teleporter Accident caused her to show her panties to the rest of her class room, even disregarding the countless people around the world that will perish that didn't even see her panties as collateral damage. Luckily, her friend stops her before she could actually use said horn.
In one of the most disgusting examples of this trope, an abusive man in Gantz beats his girlfriend's two year old son to deathfor eating the last pudding cup.
Sumire/Shiwasu Mina in Getsumen to Heiki Mina decided to declare herself Supreme Queen of Earth by forceful takeover and to put a fellow team member out of business just because she was losing against her in the overall team rankings. Just a little overboard there...
Giant Robo: The someone enacting this trope is actually the main cause for most of the events in the OVA. It turns out that Dr. Van Vogler, the Mad Scientist who nearly destroyed the world in the tragedy of Bashtarl actually wanted to stop this disaster before it even happened; his colleagues just decided to blame him since they managed to get out of there. So his son decided to use the Anti-Shizuma Drive to exact revenge on the world that "ignored the truth" by destroying society.
In Gon, this is Gon's core attribute. He frequently dispatches creatures that have attempted to eat or harm him in particularly cruel ways, such as beaching a shark that has swallowed him and feeding it a small piece of banana as it suffocates to death.
In Maou no Hajimekata its implied Aur once suffered a great betrayal that left him completely disgusted with humanity, he then proceeds to become a Demon Lord with the goal of making all of mankind be miserable and serve him as their new overlord, the catch is that Aur is the resident Villain Protagonist and the plot glorifies his deeds, he constantly tries to upstage himself in extremely nefarious schemes to bring villages and towns to his rule, to add Aur has a thing for making women his sex reliever, going for mind control and then raping to submission if they dont like him right away.
One of Mobile Suit Gundam SEED's main villains, Muruta Azrael, the leader of anti-Coordinator terrorist organization Blue Cosmos, was picked on by Coordinator bullies when he was little. His answer to that as a grown-up who should have known better? To try and annihilate every single Coordinator from the face of the universe.
ZAFT's reaction to the Junius 7 attack. Deploy N-Jammers on the Earth and shut down every single power plant. That includes the ones belonging to ZAFT's allies on Earth.
Shinn in Destiny goes a little wonky when Lunamaria is injured during the Battle of Crete. Shinn's response to his teammate being injured is too literally turn the Orb fleet into scrap metal. Befitting considering his status as The Berserker.
Speaking of Gundam, there's also Camille from Zeta Gundam. His career as a pilot started because some space-fascists made fun of his name. In real life, there are a few extreme examples of kids who got pushed around and then took a gun and shot up the school. Camille takes a Gundam and shoots up a space colony!
Then there's Char Aznable from Mobile Suit Gundam who takes it upon himself to avenge his father's death by killing all of the Zabi family, despite no full proof evidence coming forth that Degwin really did murder Zeon Deikun. It can be argued that Gihren was a monster and Kycilia was The Baroness. However, the murder of Garma Zabi, Char's own best friend, definitely counts. Seeing that Garma was actually a really decent guy to both friend and foe and trusted Char completely. Char's own sister, Sayla, comments in disgust about Char's revenge. And later on Char himself even admits it was wrong to take Garma's life and that he isn't motivated by revenge anymore.
For what it's worth, one of the original unaired episodes of MSG (specifically the ones that were removed due to the series being shortened) depicted Degwin meeting Revil aboard the White Base to discuss armistice, only to encounter Sayla and, upon recognizing her as Artesia Som Daikun, go into a frenzy begging her for forgiveness for murdering her father.
You think Garma's death is bad, try Char's actions in Char's Counterattack: he dropped asteroids on Earth and tried to cause nuclear winter (which ran counter to his father's ideals of preserving the Earth) simply to have a final battle with Amuro Ray. That doesn't stop Zeon fans from claiming Char was in the "right" throughout, either through the Earth having it "coming" over the OYW and beyond (9 times out of 10, the Zeeks are usually the ones to start said wars) or Char was legitimately trying to bring peace to the Earthsphere. The latter conveniently omits both human nature and the fact there were other militarized spacenoid factions besides Char's Neo Zeon, namely the Jupiter Empire and Buch Kozern (the latter of which would later become the Crossbone Vanguard). And that's not discounting the fact Char would have killed the Zeon remnants on Earth alongside everything else.
Over in the universe of After War Gundam X, we got the Frost Brothers. All of their actions? Was because the Earth Federation labeled them as Class F (Fake) Newtypes. note They had amazing telepathic and empathy towards each other, it wasn't enough to use the Newtype Bit System. The Federation were a bunch of dicks in that universe, too.
In Gunslinger Girl it was once mentioned that Elsa tried to break a waitress' arm because she almost spilled water on her Fratello.
Heavy Metal L-Gaim: Gablet Gablae threw himself into the task of destroying The Hero Daba and his companions, his obsession driving him to obsessively and relentlessly chase them through space and to another planet, engaging in countless mecha duels with Daba and (being defeated and humiliated in every single turn, but that is another story) What did they do to him? Having the gall to demand that he paid the food that he had stolen.
People who got sent to Hell in Hell Girl are largely deserving of what they get, if not for what they have done to the aggrieved personally. As the series goes on it becomes increasingly clear that you can get sent to Hell just for looking at someone the wrong way.
A few episodes of Jigoku Shoujo Futakomori (Hell Girl 2nd season) portray this trope. Also happened in an episode of Jigoku Shoujo Mitsuganae (Hell Girl 3rd season).
One target in season 3 gets sent to hell so the client can avoid potential minor embarrassment.
Another person got sent to hell for accidentally spilling coffee on the client.
In Higanbana no Saku Yoru ni, when Nonomiya is blamed for breaking school equipment, he retaliates by taking pictures of Yoko which ultimately turns the school against her and they make her into their plaything. She kills herself and her soul is then eaten by The Principal.
In Higurashi: When They Cry, Onryu punishes Shion by having three of her finger nails pulled off because she ran away from boarding school.
In the second, '80s Himitsu no Akko-chan series, Akko-chan breaks her Secret Identity by carelessly letting her friend know of her magic mirror and her shapeshifting abilities. The Spirit of the Mirror decides to take away her powers... along with her reflected image, thus forcing Akko-chan to hide her peculiar predicament. Thankfully, everything gets better.
Kenichi: The Mightiest Disciple has Odin, the leader of Ragnarok, who got started on the path of evil as a child when he didn't get the pin he wanted out of a vending machine, but Kenichi did. He fought Kenichi over it, lost, and has been bitter about it ever since in part because Kenichi wanted him to have the pin anyway.
Akane from Kitchen Princess tries to drive Najika out of the school just because she's the object of Daichi's affections and Akane isn't.
Oburi from Kite sets himself up for Laser-Guided Karma example of this trope. After his new jacket is dirtied by a wet basketball that accidentally hit him, Oburi shoots the basketball, much to the anger of the two children that demanded the ball back and were mocking him, especially the little girl. At the end of the film the little girl shots and kills Oburi while he's walking by to meet up with Sawa.
Both the grievance and the response are delivered accidentally in Kyou no Go no Ni's first episode. When Yuki and Megumi get hit on the head (accidentally) by two high-bouncing "Superballs", and then hit again on the upbounce of another round, cue an argument ending with Yuki accidentally slipping on said superballs in such a way as to deliver a perfect Groin Attack to Ryouta. Needless to say the matter is considered settled after that.
In Laughing Salesman, Moguro's disapproval and disappointment when some of his clients breaks a promise, a deal, or just his trust is understandable, especially in cases where his help actually does make his client's life better. But when he strikes back, he usually goes overboard.
Love Hina is full of this trope. So Keitaro ends up walking in at a time that he shouldn't, so he gets beaten up and humiliated by the residents (all female) at the Hinata inn (as well as at least one Death Threat). Said incidents include when they are changing or at a bath. Even when it is actually one of the girls who walks in on Keitaro when he's changing, he gets beaten up anyways.
Mahou Sensei Negima! has a number of things like this, but the most ridiculous is probably the time that Asuna managed to nick Evangeline's cheek. Eva's response? Lick the blood off and encase Asuna in a block of ice. Fridge Horror sets in when you realize that Eva is a vampire who can regenerate any damage anyway, that this took place during a training exercise, and that if it weren't for Asuna's Anti-Magic, she would have been encased in ice for ten years.
Marvelous Melmo has the titular heroine, a 9-year old girl forced to care for her even younger siblings because of her mother's death receives a box of magical candies able to age her to adulthood and de-age her, with the express purpose of being able to care for them. However, since the angels responsible for her take them back when she abuses her power for selfish reasons (date a guy in his late teens, using the added shape-shifting abilities of the candies for making things easier...). At the very same moment, Melmo had just turned herself into a dog, and as such she gets unable to properly care for her siblings or interact with every human soul, even risking to be captured and "put to sleep". The whole while the angels and Melmo's dead mother, in Heaven, argue about Melmo's fate. Eventually the punishment gets partly amended, becoming more proportionate: Melmo's power is restored, thus making her able to resume her human life again and care for her siblings, but with a finite number of transformations, thus forcing her to be more careful.
The fate of several girls in Master of Martial Hearts: if the sheer fact that every fight in the Platonic Heart tends to turn into a death match, it gets worse when you're made aware that actually the losing Action Girls suffer A Fate Worse Than Death itself. They're actually saved, nursed to health and then mindraped to the breaking point and sold into sexual slavery. Just to get sure, many of them get their voice box removed, thus explaining how one of the previous generations loser, after escaping her destiny, became little more than the resident Cute Mute and harmless mom. Tinged with Misplaced Retribution, since Natsume, the daughter of the aforementioned Cute Mute, organized a second edition of the Platonic Heart, thus reaping a whole bunch of completely random strangers, just to lure out the daughter of the organizer of the tournament costing her mom her voice and freedom.
Natsume and Miko's grandfathers killed the families of Aya's parents, so they started the Martial Hearts tournament specifically to target their children. One generation later, Natsume and Miko themselves, upon learning what the fuck had gone down, orchestrate the aforementioned copycat crime ring just to get back at Aya for what had happened to their mothers. This fucks up her brain so badly, the series ends with her trying to put an end to the Cycle of Revenge once and for all before it gets any worse than just "an eye for an eye [leaving] everybody blind".
Dr. Hell from Mazinger Z killed a dog when he was a little child because he thought the mutt was glaring at him. You could tell his sanity was already very strained back then. Also, he was abused by everybody when he was young, so naturally, making plans to Take Over the World and enslave all of humanity is a proper punishment for wrongs that were made several decades ago by other people.
Miss Kobayashi's Dragon Maid: At the beginning of episode 5, Tohru blasts a couple of birds that were pulling on the laundry she hung out to dry. Said blast presumably destroys the birds, along with the clothing, and the balcony, though it seems she fixes it with magic after the opening credits are done.
My Bride is a Mermaid: Lunar hates Sun and constantly tries to make her life hell because Sun beat her in a singing contest when they were kids.
My Monster Secret: Akane really likes candy, to the point where she's attempted to end the world via meteor because someone deprived her of her snacks. Twice.
Narutaru's villains love this trope. For starters, Satomi Ozawa develops a murderous grudge against the heroine that started just because she made fun of the name of her school. Later in the manga, Naozumi Sudo shoots two delinquents to death just for throwing a bag of trash in a river...
In Naruto Uchiha Sasuke after finding out that Itachi was under orders by Danzo, Sarutobi, Koharu, and Homura to execute the Uchiha clan for treason and an attempted coup that would result in a costly civil war, he apparently decides to MURDER EVERYONE! Danzo, Homura, Koharu, the villagers of Konoha (who had no idea about the attempted coup, much less that Itachi's genocidal actions were sanctioned), innocent samurai who are only doing their job, etc. Apparently the only way to make everything better is to go on a genocidal rampage that would make Pain green with envy.
Also, on one occasion when Jiraiya was caught peeping on Tsunade bathing in his younger years, she proceeded to break both of his arms, six of his ribs, and ruptured a number of his organs as punishment. Yamato even said Jiraiya came very close to dying that day.
In fact, Jiraiya himself admits that's one of TWO times he came close to dying, with the other being Naruto losing control of his Kyuubi-mode.
Danzo could be a Well-Intentioned Extremist version of this. He had a very black and white viewpoint about how ninja should operate, to the point that seeking a Heroic Sacrifice is one of the best ways to prove one's worth. In his backstory during his death, he has the slightest of hesitation to fill that role during the last war. The Second Hokage refuses both his and Sarutobi's offers in order to do it himself, picking Sarutobi as the third. What does he do as retribution? He creates a martial faction of the Anbu which he uses to hide numerous secret enhancements to his body which came as a result of connections to known criminal Orochimaru, all of which lead up to him using mind control in order to take control of the village and eventually attempt to control the ninja world. He's found out, however, and is told that if he had done things nicely, he'd have probably gotten his way anyway, but because of his brainwashing, he can't be trusted. What's worse, before his hacking into being Hokage, he waited while Pain was destroying the village. If Naruto hadn't won the fight, there wouldn't have been anything left for him to rule over in the first place.
Years before the events of the main story, due to some men from the Hidden Mist village abducting Rin and turning her into the Three-Tails' Jinchuriki, and ultimately being responsible for her death, Obito Uchiha, posing as Madara, Mind Controlled Yagura, the fourth Mizukage. Under the influence of said mind control, Yagura essentially forced innocent children to graduate by murdering one another, and then perpetuated the Bloodline Massacres, resulting in the nigh extinction of several clans (including Haku's and Kimimaro's) and ostracizing the surviving Kekkai Genkai users, forcing them into hiding for fear of being killed. Becomes even more Harsher in Hindsight when we learn that Madara was behind the Hidden Mist's role in Rin's death, all in order to get Obito under his control — Obito condemned innocents for something neither them nor their village had anything to do with.
The island of Ohara was subjected to the Buster Call, which is an assload of warships pelting the place with giant cannons until there's nothing left. Their crime? Researching the history of the world. (It is disproportionate in that everybody but Nico Robin was blown to smithereens, including non-researchers, but the subject matter did contain some information which the World Government didn't want out.) It's implied that the government didn't put much effort into hiding their displeasure of Ohara's research. And, they even ruined Robin's childhood because they think she might know how to read Poneglyphs (she can but they didn't know that at the time). To put it lightly, they called her "Devil Child", claimed she was a killer who had sunken six ships, and put a bounty of 79,000,000 berries on her head. When she was eight years old.
Near the beginning of the series, Axe-Hand Morgan decreed that anyone who tried to feed a prisoner tied to the cross in the courtyard would be punished for the prisoner's crime. A little girl, not eight years old, would have been executed for trying to feed Zoro if Luffy hadn't defeated Morgan.
Morgan thrives on this trope, considering his Hair-Trigger Temper. Later on, he has a couple of his soldiers stand up a statue of himself by pulling it up with ropes. One of the soldiers accidentally pulls his rope too hard, barely damaging the statue's hand as it bumps on a nearby spire. The poor guy tries to apologize, but in Morgan's eyes, this is a sign of disrespect and is nothing less than a traitorous activity that's punishable by death!
In the flashback to Luffy's childhood, Saint Jalmack sinks Sabo's boat and possibly kills him for cutting in front of the ship the World Noble was on. He could have justified it with Sabo's pirate flag, but he gave the crossing paths excuse higher priority.
When Luffy punches a World Noble named Charlos for shooting Hachi, Charlos's father calls in the Marines, including Admiral Kizaru, to the island, and then declares his intention to starve the men of the crew to death while working them as slaves and have the women stuffed, overlapping this with Knight Templar Parent and Moral Myopia. Before that, Charlos kicked over a wounded man who was being transported to a hospital and shot one of the paramedics carrying him because they dared to not bow before him as he walked by. If that wasn't bad enough, he kidnaps the wife of the man because he found her pretty and wanted her to be his wife. (The World Nobles seem to exist for little reason than to be Hate Sinks in charge of the World Government.)
They've done horrible things to people for far less. Another one shot two small children sixteen times for running in front of him!
Charlotte Linlin AKA "Big Mom" (one of the Four Emperors) provides protection to any country, but only if they give her payment... in sweets, that is. In the case of Fishman Island, it had to produce ten tons of candy monthly for Big Mom. With that said, would she really be willing to penalize an entire country for not giving her sweets on time? Yes, she would, by obliterating it!
Baby 5, one of Doflamingo's underlings, is known to appease someone whenever she is needed. Thus, all eight of her fiances were men who somehow "needed" her, not because she actually loved them. These men were also quite obviously sleazes and swindlers taking advantage of her. While it would make sense why Doflamingo would kill them (or else Baby 5 would have gotten attached to them), it does not make sense for him to kill them andburn the residing island to the ground.
Akainu killed a marine officer just because he wanted to leave the battle so he could see his family.
Subverted in the Dressrosa arc: after Doflamingo initiates his "Bird Cage" plan, he forms a blacklist of twelve people he wants dead, assigning bounties on their heads. Usopp gets a bounty of 500,000,000 Beli, which initially seems way overblown considering he's one of the weakest, if not the weakest of the list. However, Doflamingo didn't assign him that high a bounty because of his strength, but of his role: because Usopp knocked out Sugar, all the people she had turned into toys returned to normal and the truth behind Dressrosa was revealed, putting Doflamingo in a very sour mood towards Usopp.
Played straight with Doflamingo's actual motives for his activities as a pirate — which seems to be par for course for the Celestial Dragons. Doflamingo's father apparently grew tired of the decadence of Mariejois, and decided to forfeit the family's titles as World Nobles in attempt to live the normal, commoner life. Doflamingo despised this decision, so used to the broken privileges bestowed upon the descendants of the twenty kings who found the World Government, and eventually ended up killing him two years after his mother died by illness — something he blamed on their commoner lifestyle. However, when he and his brother attempted to return to Mariejois, the World Nobles rejected their plea, considering them to be a part of a "family of traitors". Doflamingo, angered by this decision, swore to destroy the entire world they lorded over in retaliation. His behavior is more or less alike to that of a spoiled child who didn't get what he or she wanted — so pathetic, that the only reason why he's such a threat is because he's downright psychotic.
Pica, one of Doflamingo's top executives, is a huge, muscle-bound guy... with an impossibly high, squeaky voice. If anyone dares to laugh at his voice, he responds by burying the offender alive.
Also, Luffy and Blackbeard could have been the best of friends, had not a fight between them started the day they met when each insulted the other's favorite food. Luffy didn't like the brand of cherry pie the store had, Blackbeard wasn't a fan of well-done meat; both got annoyed at the other's complaining, and a fight started. While many other factors contributed to them being sworn enemies, this likely started it.
Played for laughs with Carrot, who once tried to tear Luffy's throat out simply for taking one of her carrots.
In One Piece Film: Gold, one of Gild Tesoro's subordinates dares to laugh at something without his boss' permission. Tesoro immediately responds by encasing the poor sod's head in gold and lets him suffocate. Granted, one factor in Tesoro's Dark and Troubled Past as a slave of the Celestial Dragons/World Nobles was being punished for laughing without permission, but the guy was drunk and probably didn't even realize what he was doing.
In Paranoia Agent, Tokyo is leveled due to Tsukiko Sagi lying about how her dog died when she was in grade school.
Harley comes in seemingly innocent in his debut episode and acts all nice to May, a fellow competitor. Then, May makes a few innocent comments (calling his Cacturne scary and saying that his cookies aren't half bad), which causes him to apparently change his goal in life to humiliating her at every contest that they participate in. (It's even worse in Japanese, where his reaction is to her Verbal Tic.) He later acts as something of a borderline parody of the trope, continuously trying to destroy May throughout the show for minor slights like beating him in a battle. In a later episode he finally reveals the deepest reason for his raging vendetta, that being, as a kid he once got part of his meal stolen by a girl who kind of looks like her and even that may have been made up.
Dawn has ended up in a similar experience with one of her rivals, Ursula. Why does Ursula have a vendetta against Dawn? One of Dawn's Pokémon didn't like Ursula's Poffins.
Then there's Paul, who feels the best way to prove himself a better trainer than his brother (who lost to Pyramid King Brandon in a Curb-Stomp Battle) is to crush the morale of everything he can possibly reach?
James has shades of this. He really likes his bottle cap collection. When it had been (accidentally) stolen by a trash-collecting robot, he tried to steal the Sunnyshore Tower. In other words, he tried to steal a bloody skyscraper. What truly seals the craziness is that that was Team Rocket's evil-plan-of-the-week...and Jessie and Meowth were still freaked out at James' sudden gung-ho attitude! This doubles as Beware the Nice Ones: One episode saw a pack of baby Pokemon (including James' own Mime Jr.) in danger. James agreed to help out almost immediately—and he reacted...violently when Jessie and Meowth refused to help. Both of the above instances happened before Team Rocket Took a Level in Badass.)
Back in Johto, the Terrible Trio stole the Crystal Bells and accidentally break one of them while running off. What happens? Every last wild Pokemon attacks not just Team Rocket, but any human in sight including Ash and the gang, who didn't do anything!
Way back in the beginning, Ash ended up in a perfumery in Celadon City and ended up getting banned because he insulted the perfume. Not so bad, but the perfumery was actually the Celadon City Gym and the person who banned him was the Gym Leader, Erika. Thus, his Pokemon journey nearly came to an end (never mind that in kicking him out Erika was in violation of gym leader protocol, as Misty soon points out) because he insulted perfume. When Team Rocket got banned, they responded by not only helping Ash get in (in the guise of a girl), but also by trying to burn down the gym.
Then there was the little incident in Johto (Azalea Town to be precise). The folks there are apparently so fond of Slowpoke that when Ash simply stepped on a Slowpoke's tail, it seemed everyone in town was after his head before he could explain it was an accident. (Fortunately, everyone forgave him once he helped Kurt save the Slowpoke in the caves.)
Clemont, one of the main characters in Pokemon XY and leader of the Lumious City Gym, built a robot to replace him while he dealt with his inventions. However, he didn't do too well building the thing and it kinda went out of control. As in, it would electrocute those who either didn't have four Gym Badges or failed the Gym Challenge then threw them out from a tall height with nothing but concrete to break their fall. Needless to say, Clemont fixed this problem post haste once he learned of it.
In Pokémon Adventures, the Sinnoh Trio make a lot of noise in Mt. Coronet's caves. Cyrus feels that burying the three twelve-year old children in a rock slide is the appropriate response.
In the FRLG chapter, one of the two Deoxys Team Rocket captured and experimented on was understandably miffed after it was trashed. However, it retaliated 3 years later in the ORAS chapter, directing a meteor to destroy the entire planet.
The case: Ranma has shown up at the Tendo Dojo and plunged it into chaos by revealing he's a boy who's been cursed to turn into a girl when splashed with cold water. The crime: in response to Akane's various derogatory comments, primarily accusing him of being a pervert for seeing her in the nude when she walked in on him taking a bath, Ranma declares it's no big deal for him to see a naked girl, as he can just turn into one anyway, and then adds in an off-hand matter that his female form is better built than Akane is. The response: Akane grabs the table and belts Ranma over the head with it from behind, knocking him out cold.
The case: Ranma, in female form, has been kissed by Mikado Sanzenine. The crime: Ranma is actually a straight boy, with Mikado not knowing either that it was Ranma's first kiss or Ranma's true identity. The response: Ranma (who has enough Super Strength that he can split boulders without trying too hard) turns into a male and hits Mikado over 500 times leaving Mikado unconscious on his feet.
The case: any outsider woman has defeated a female member of the Joketsuzoku. The crime: defeating the female equivalent of one of the closest things Ranma 1/2 has to a Proud Warrior Race Guy. The response: a symbolic Kiss of Death, followed by the defeated Joketsuzoku pursuing the outsider all over the world until one or the other of them is dead.
The case: Ranma has distracted Happosai, causing him to get hurt. The crime: Ranma's interference in one of Happosai's pantyraids allowed the angry women to catch and beat up the Dirty Old Man. The response: Happosai burns a moxibustion on Ranma's back that leaves him weak as a baby, then distributes fliers about how Ranma is weak all over town, gloating to Ranma that this means his various enemies will seriously hurt and perhaps even kill him, without Happosai needing to lift a finger.
Ryoga is basically this trope personified, as his grudge over Ranma was that Ranma would inevitably beat him to the last meal sold at the school's lunch store (and this wasn't even technically Ranma's fault: due to Ryoga having No Sense of Direction, he would always arrive just too late to buy any food), and then Ranma "no-showed" when Ryoga challenged him to a duel (it was actually Ryoga who no-showed due to the aforementioned directional issues) and their relationship has only deteriorated since, the two of them at odds unless Akane is in danger.
In Ryoga Inherits the Saotome School, Genma practically disowns Ranma, takes Ryoga as his student, trains him to take over the Saotome School of Anything Goes Martial arts and become Akane's fiancé', while teaching him Ranma's weaknesses and arranging a fight between the two in order to publicly humiliate Ranma. All because Ranma ate a manju pastry that Genma was saving for after work.
RO-KYU-BU! shows just how far a school's administration is willing to go to quash suspected pedophilia amongst its students. If even one member of any club so much as makes out with a girl that's so much as three years younger than he, you can say goodbye to the entire club for the next year, and the offending party is forever branded a traitor to his club. This happens at the very start of the series, where Subaru's plans to play high school basketball are derailed by the team captain's alleged actions.
In Rosario + Vampire, everything Gyokuro did was because her husband liked his mistress Akasha more than her.
In Rurouni Kenshin, Enishi wants to take revenge on Kenshin for unwittingly killing his sister, Tomoe during the Bakumatsu. Whilst Kenshin believes Enishi's grudge is perfectly understandable, the methods he and his 'comrades' resort to ( blowing up property, injuring people, kidnapping Kaoru and faking her death etc.) are rather...extreme.
Sailor Moon S: Mimet stole Telulu's job from her. Telulu's response? To send Mimet falling into a void of nothingness. Which either kills her or traps her in darkness for all eternityLaser-Guided Karma since Mimet did the same thing to her predecessor Eudial by sabotaging her car. In-Universe, Sailor Moon looked utterly horrified at Mimet's fate.
In Saint Beast, Zeus' insane punishments are made all the more clear by the Double Standard treatment certain angels get. Shiva leads a demon into heaven to kill Shin and gets a warning. Judas and Luca start a war against Zeus and get banished to hell. Those three angels who happened to be really arrogant? Purged, and their resentful ghosts trapped in a dark pit.
School Days has become famous for endings where at least one brutal murder takes place among the three teenage main characters — either for sleeping around or just for being the hypotenuse.
Natsumi of Sgt. Frog is this trope and then some. Yes, she is sharing her house with an alien frog bent on world domination but she loves beating him for anything that slightly annoys her. Forget to wash the dishes? Beating. Say something insulting about her, even though she always calls him a stupid frog? Beating. Look at her funny? Beating.
In response, Keroro himself sometimes goes into this when he plans revenge against Natsumi. One episode has her throw soybeans at him and call him an oni, which is admittedly nasty—but not nasty enough to turn her into an oni and relentlessly bombard her with soybeans until she surrenders the household.
Lina Inverse, main character of Slayers, does this a lot — sometimes she seems to have only two levels of punishment: shouting, and blowing things up. It's primarily this willingness to fly off her head over little things and react by throwing around Sphere of Destruction type spells that gives her such a bad reputation. The biggest examples are her blowing up a restaurant for stepping on her own sardine (amidst complaints saying that she didn't want it in the first place), and nearly drowning Amelia in a hot spring after the latter makes an innocent joke towards her.
This is woven into the premise of Special A. Hikari lost a wrestling match against Kei as a kid, which was apparently enough to turn her into a determinator set on beating him at something. Unfortunately, most of the time for her, Failure Is the Only Option.
Mantid in Spider Riders seeks to kill every person in the Inner World, because he blames the Oracle for the death of his love, Lorraine, and resents spending time fighting for her when his real home was the Outer World.
This seems to be the MO of Akane Shinjo in SSSS.GRIDMAN. She creates clay sculptures of monsters which are then brought to life as Kaiju by by the Big Bad. Her reasons for doing so is usually to exact revenge against those she feels have wronged her in some way. For example, she has a kaiju murder her classmates in the volleyball team...because one of them knocked a hot dog she was giving to the protagonist out of his hand, ignoring the fact that it was an accident and she apologized profusely for it. While it's worth noting that damage to the city (which is almost always completely leveled by the time the fight is over) is mysteriously undone the following day and everyone who isn't directly involved with the titular hero or the aforementioned Big Bad loses their memory of the event, it still says a lot that she's willing to go so far in the first place.
During his introduction, Juuzou Suzuya is given a hard time by a police officer because he was found covered in blood and wielding a knife. The victims were Ghouls, so killing them was fine but he's arrested since they won't believe he's a Ghoul Investigator due to his unconventional appearance. When he's finally picked up by his partner, Juuzou takes revenge on the officer that gave him a hard time.....by sucking the man's eardrum out and stomping on it. Later, he steals the motorcycle of a superior that mocked his androgynous looks and crashes it in a truly epic explosion.
In the sequel, a rookie Investigator recognizes Seidou Takizawa and tries to talk him down using the fact he once gave a lecture to her class at the Academy. He cheerfully recalls she was the girl that kept talking in class, and when she agrees....he shoves his arm through her chest and decapitates her, scolding her for not paying attention.
In the first chapter of Tokyo Mew Mew, Zakuro breaks a girl's arm simply for bullying Retasu in a rather petty manner.
In Tomica Hyper Rescue Drive Head Kidou Kyuukyuu Keisatsu, Karigari has reason to be upset with Kurumada for crushing his dream (Kurumada being the reason the robot he designed was rejected in favor of the Drive Head project). However, the elaborate revenge plans he constructs, especially the time he outright tried to burn down the Mobile Rescue Police headquarters, definitely go beyond simply getting comeuppance.
In Musou Kakyou: A Summer Day's Dream, Patchouli Knowledge, already rather stressed out due to Reimu Hakurei, the protagonist and resident Miko, interrogating her about her donation box which was stolen from her shrine, gets hit in the face with one of her own books, thrown by Aya during a heated argument with Marisa. Patchy gets very pissed at this and decides to take it out on Reimu. After a short scene with Sakuya and Remilia, we cut back to the library and Patchy is busting out "Sun Sign: Royal Flare," one of her more powerful spellcard attacks. Reimu herself doesn't exactly hold back in her retaliation either.
In 20th Century Boys by the same author, second Friend is ready to annihilate mankind as "unworthy to live" because one of his childhood friend once committed a petty theft and let him take the blame. They were about 9 years old at the time. The consequences were that Friend was symbolically executed and everyone pretended he was dead. This was done so thoroughly that, as adults, everyone from that clique thought he was really dead. Which should be considered Disproportionate Retribution as well.
In Urusei Yatsura, Ran is always thinking of new ways to torment her initially oblivious friend, Lum, because Lum constantly got her in trouble as a child (sometimes on purpose, sometimes not, but never maliciously) and accidentally stole the guy she likes. She even takes this so far as to help her rescue Ataru from a rival alien princess in The Movie just because if anyone's going to steal Ataru from Lum, it's going to be her, because at least she has a reason for doing so (unlike the rival alien princess in question), even if said reason is a bit unreasonable.
Wolf Guy - Wolfen Crest: Haguro beat his Noble Demon subordinate Chiba within an inch of his life, biting off his tongue, and then raping him for good measure to the point that Chiba ends up dying from a combination of ruptured organs, blood loss, and broken ribs. Thankfully, Inguami gave Chiba some of his blood which ended up bringing Chiba back to life. Why did Haguro do such a thing? Because Chiba ended up encountering Inugami out on the streets and talked to him for maybe 15 minutes when Haguro wasn't around, and Haguro's Yandere streak kicked in.
In xxxHoLiC Watanuki and Doumeki accidentally broke a spider web while doing some garden cleaning. The spider took her revenge by stealing Doumeki's eye. Considering that it takes about one hour for a spider to construct a web we could say that she overreacted a bit.
Yu-Gi-Oh! is notorious for this. Yugi was the target of several ill-conceived vengeance plots throughout the various seasons. One particular example had the daughter of one of Yugi's grandfather's friends challenge him because his grandpa "stole" her grandpa's rare card.
Jerkass Seto Kaiba does this to an extreme in the manga version, where he traps Yugi and his friends (and a toddler one of them happens to be babysitting) in "Death-T", a gauntlet of murderous trials and challenges where failing could lead to death. Seriously, hiring professional assassins for a REAL laser tag, electric chairs powered by screams, hiring a SERIAL SLASHER... and the reason for all this? Because Yugi beat him in a card game (which Kaiba himself tried to cheat in.) He claims he spent a billion yen on this place (about $10 million in American money).
Kaiba's revenge wasn't just for his defeat, it was because of the Penalty Game that the Pharaoh put him through after he lost. For the crime of stealing his card and threatening him for it, the Pharaoh trapped Seto in an illusion where he experienced his own death. This was actually perhaps the most merciful that the Pharaoh's Penalty Games have been. In this case, he meant for the experience to help change Kaiba's ways. What actually happened is that Kaiba was traumatized enough to have recurring nightmares about the experience (The fact that Kaiba had been operating on a severe Lose=Death mentality thanks to his stepfather at the time didn't help). In fact, in order to make his revenge more complete, he built a technological version of the penalty game, using holograms, to subject Yugi to. Eventually, the Pharaoh got sick of all the revenge schemes, and just blew up the evil part of Seto's mind. He came out of it a sort of changed man. Granted, it put him into a coma for nearly a year, but still.
Interestingly though, this is played completely straight in the Toei anime since Kaiba doesn't experience the Penalty Game (he escapes by ending their duel monsters game in a draw...somehow). Basically, Kaiba takes this trope Up to Eleven by hiring Game Masters to take down Yugi, and eventually setting up Death-T...because Yugi didn't let him steal the Blue Eyes, and tied him in Duel Monsters. Also worth mentioning that the Toei anime didn't include Gozaburo's abusive child-raising and the on-screen takeover of KC was less The Dog Bites Back and more Seto Kaiba is a power-hungry Jerkass which does away with his Freudian Excuse...you're really just left wondering what this Gozaburo did to piss Kaiba off...
Another had Duke Devlin, a would-be game developer, challenge Yugi to a duel because he thought Yugi cheated to beat Pegasus (which is debatable—Pegasus was already using his Millennium Eye to cheat, first with the Mind Scan, then with a Shadow Game that injured Yugi, so whether or not Yugi and Yami's Mind Shuffle counts as cheating is pretty YMMV) and killed him (which he didn't), thus ruining his chance at getting his designer game produced (the fax green-lighting it came in less than an hour after the duel), with the stakes being his friend's freedom, his champion title, and his right to play the show's Serious Business card game forever. To Duke's credit, he does get the hint and eventually forms part of the show's extended cast, helping out at times.
The punchline is that all of the above cheating methods were never publicized at all, only the final result. Duke was convinced Yugi cheated out of sheer denial that anyone could ever defeat Pegasus fairly.
Duke's reasons in the manga were a bit more justifiable, since he had to do it for his Monster Clown of a father in an act of vengeance for whatever Yugi's grandpa did to his face.
Duke's father is a much stronger example of this. He and Solomon Moto played the Devil's Board Game, whose cursed power aged him immensely when he lost. Thing is, they both agreed to play the game (for whatever insane reason), and the rules of the gamenote take turns rolling a die moving a game piece that number of spaces towards the center of the board. are such that one's opponent has no bearing on who wins the game. One can't take revenge on the Random Number God, so imprisoning, discrediting, and murdering Solomon's grandson, after forcing him to play the Devil's Board Game, was apparently the next best thing.
Yami Yugi does have quite a Disproportionate Retribution thing going on, though, especially in the early manga before Yugi puts his foot down. Most of the people he challenges to Shadow Games are unpleasant, and the games are always fair (that's part of the rules) but still... look at Duel 6, Into the Fire. These guys stole Yugi's group's space and injured Yugi, so Yami blew their leader up with explosives. An extortionist bully threatens Yugi and cheats at the shadow game, so he's made to wallow in a pit of trash while thinking that there's nothing but money raining everywhere. A director uses his authority to lie about Yugi and his friends, so the Pharaoh blinds him (in an ironic way). Hilariously, Kaiba's Disproportionate Retribution is the result of one of the Pharaoh's most merciful Penalty Games. Sure, Kaiba was driven mad by the traumatic experience of feeling his own death, but at least he's still alive and functioning.
Minor example and an aversion in Yu-Gi-Oh! ZEXAL during the two-part Duel Coaster episode. V was about to go ballistic on Yuma because he lost only 400 Life Points from Yuma's attack (and V had used the House Rules of the Coaster to increase his points to far more than he started at) and only backed off because Tron told him to. (Of course, later episodes show V to be an egotist in every sense of the term, so this makes sense in hindsight.)
In the manga Yu-Gi-Oh! D Team ZEXAL, the very unsubtly-named villain Master Evil's motive for destroying the entire Duel Carnival (possibly killing his two henchmen after their deathtrap-based duels failed) was because he was disqualified from the last Carnival. (He claimed it was because his deck was too powerful and opponents fled from him in fear, but the real reason is, he had been cheating.)
An older boy in Yu-Gi-Oh! GX that Judai looked up to used a trap card to stop him from summoning Yubel in a duel when he was a kid. He was fairly upset... so Yubel put him in the hospital. When Judai visited the boy later, Yubel did something that made him scream. Small wonder nobody wanted to play with him, because they kept doing these kinds of things.
And it must be remembered that this was before Yubel's "corruption" by the Light of Destruction, which only served to increase the scope of Yubel's crazed actions, affecting their core nature not at all.
K from I Wish put a curse on his real name that will cause those that speak it unbearable harm... because some kid used to make fun of his name.
In Dorei Shouni Shika Sentakushi Ga Nai Desu Yo, Zeolith suffers from this near constantly. Any of the women in his sphere of influence feel slighted, and they will come at him with deadly threats. The manga even begins with Zeolith admiring the scenery on a hillside and a massive fireball coming for his head, and then a dagger flying right past his ear into a nearby tree. The "crime"? Forgetting that he promised his two female childhood friends that he'd "train" them in magic and knife-fighting respectively.