A character who seems particularly adept and eager to take down bully-type characters with extreme prejudice, or at least show he has this streak in him. The Bully Hunter may do it by accident or while passing through the area, or he may actively seek out those who make others' lives miserable as a pastime and inject some hell into their lives in retaliation.
The high-school version of the Vigilante Man, these kids prefer to take matters into their own hands rather than wait for a teacher to sort the problem out. They may believe that teachers are useless when it comes to dispensing justice, or that while the teachers are competent, the school system isn't.
Such characters must be wary of running afoul of He Who Fights Monsters. At times, the line between bully, bully hunter, and victim are thin indeed. Often saves the world occasionally on top of his playground-peacekeeping activities. Sometimes from the bully. These are also the characters most likely to make the life of a Sadist Teacher hell. Other members of the faculty will either see him in action, misunderstand the situation and punish him alone, or if that person does know what is going on, will pull him aside to advise him on a more constructive means to deal with school bullying.
Can be a result of Bullying a Dragon or Mugging the Monster when the bully victims themselves are the ones who fight back. Can overlap with Big Brother Instinct if it's a specific person the bully hunter is protecting.
There is an adult example if the person is standing up to bullies in the workforce. If you punch out the guy at work who is tormenting his underlings, that comes under the grown-up version of this trope. If you're out fighting muggers, however, you're looking at a Vigilante Man. And if you take this to the extreme, you can end up as a Serial-Killer Killer.
The appeal of this trope is obvious; everyone who has been bullied at some point in their lives will instantly sympathise with the urge to give a fictional tormentor a commuppance. As such, this can be a good way to introduce a heroic character as a guy or gal you can trust. It can also be used to give a backstory to an anti-heroic character if the bully hunter takes things too far; He Who Fights Monsters can be hinted at. All in the simple act of standing up to a bully.
Sendoh Takeshi from Hajime No Ippo became a delinquent only to protect others from bullies and other crooks, going so far as to to make his own gang. When his grandma calls him a scumbag, sportswriter Mari answers "But he never bullied the weak, right? He was a righteous scumbag."
This is explained by his backstory. He once was brutally beaten up by highschoolers when he was in primary school, and he hated himself for not being able to protect his friends. The next day, little Sendoh grabbed his baseball bat and ambushed the bullies, beating them back as punishment. And one thing led to another soon...
Ichigo Kurosaki of Bleach takes a dim view of bullies and has an outstanding ability to fight them even before his transformation into a Shinigami. He takes down three bullies with extreme prejudice to defend a ghost, of all things, and it's later shown in a flashback that he defended Sado from an attack by groups of thugs, who was more than capable of defending himself but didn't due to his Actual Pacifist nature.
Ichigo continues doing this after he is depowered at the end of the Hueco Mundo arc, this time with the help of not-friend Uryuu Ishida who has taken up his duty to defend Karakura of supernatural threats.
In that same episode, Mitsuo, the bullied kid, later decided he would show them what being picked on by somebody bigger than you feels like, when an unknown lady showed up all of sudden and offered him borrowing her Humongous Mecha to take revenge (and he agreed. Oh, my God) Of course, that went so well how you would expect.
Sora of Shitsurakuen is a female Knight In Shining Armour who fights to stop the boys from bullying the girls which they claim as their own. Sadly, the odds are pretty much against her.
Ranma from Ranma ½ does this occasionally — for example, she stopped Kodachi from beating up the Furinkan gymnastic team further, rescued Gosenkugi from a group of masked kids trying to rob him, and sought a direct fight with Mariko Konjou when when Akane and the volleyball team were defeated and humiliated by her tricks.
Ryoga too, most notably for defending a Brought Down to Normal Ranma from the rest of the males on the Nerima Wrecking Crew, since he thought that it was not fair to have them gang up on him in such circumstances.
Shampoo, in the episode of the Killer From Jusenkyo. When the Jusenkyo Killer had Ranma and Genma hoisted up on a rope, Shampoo jumped in to attack him despite being in cat form at the time. She also saved Ranma from Mousse when he tried to splash him with Spring of Drowned Duck water. Also in the 1st Movie, Shampoo saves Ranma and Lychee from Monlon, telling them to go on ahead while she deals with her.
It should be pointed out that she only seems to jump towards Ranma's defense, mostly because she is in love with him. She's quite selfish towards others.
Akane is also a good example. More than once, she has tried to defend Ranma from the Nerima Wrecking Crew too, and kept trying to help Ranma fight off Ryoga during their first fight. And she's not this only towards Ranma: she also steps in to defend her friends when Happosai is around, and right after Ranma saved the gym team, she accepted to fight Kodachi for their sake - despite not being good at more artistic gym styles.
Seiji Sawamura of Midori no Hibi. Strong as he is, he only fights with bad people (i.e. other delinquents, who are mostly shown to be real scum) and he protects the weak. Deconstructed in that the other gangs start to target the people around Seiji just to challenge him, something Seiji is aware and not proud of.
In the first episode of Zeta Gundam, Kamille gets beaten up by Titans military police. Later in the episode, he comes back in a Gundam and tells the MP, "Wanna know how it feels to be picked on by somebody bigger than you?", before taking off to join La Résistance.
The earliest record of Nanoha shows her being one of these, who caught Arisa bullying Suzuka and slapped her. Naturally, this ended up flowing into her career in Magical Girldom and the military.
Makoto Kino of Sailor Moon was expelled from her old school for fighting bullies, and her first appearance in the original anime has her beating up a bunch of guys who are harassing Usagi on her way to school.
Ryoma Echizen from The Prince of Tennis doesn't show much emotion about it, but he really doesn't like it when his friends and teammates are bullied. See the beginning of the Yamabuki arc as one of the biggest examples: when a whole tennis team started bullying his Fragile Flower friend Sakuno, Ryoma stepped in and defeated everyone in the team as punishment. The only exception was when Kachirou had a fight with Arai, but that was because he wanted Kachirou to prove his own strength. And he did.
An and Tomoka, too. Both girls detest to see abusive situations and will call out the culprits even if they're at risk for it.
This is the entire premise of Holyland. Though Yuu's initial purpose in going to the city at night isn't to beat up anyone, but to find his place in the world, he ends up confronting and fighting many bullies and gangsters. Initially for self-defense, but he eventually progresses to justice. He even makes friends with a few of his defeated foes.
Sonoko Suzuki from Detective Conan became Ran Mouri's friend by protecting her from bullies when they were little girls.
The girls' backstory make this a far more Serious Business; a certainly bully caused 10 Bully Hunters from 4 elementary schools to form The Alliance and engage in warfare against the former. They barely made a draw.
Shota Oruha in Takamagahara uses his powers to fight bullies, presumably. However, what he considers a "bully" is incredibly skewed to where he just attacks anybody who isn't as low on the social ladder as he is, along with the protagonist simply because he was seen in the company of an actual bully and the bully didn't attempt to harm him.
Miki always hunts delinquents and Yakuza underlings… but not For Great Justice, but because she loves violence and to slack at his job.
Makiko stops Miki’s bullying, only because she needs Miki to work for her, or when Miki is being a true Jerk Ass.
Megumi has been bullied practically all her life by Miki, and as the Hypocrite, she cannot recognize that she has a case of She Who Fights Bullies… and that Miki is the only bully she seeks revenge on.
Kankuro was bullied by Miki in the past, and he has come back to his old town trying to stand up for himself. Unfortunately, he is trapped in a Cycle of Revenge that didn’t let him get his desired Character Development.
In Yu-Gi-Oh!, Ushio first presents himself as one, but turns out to be a bully far worse than those he beats up. Yami Yugi pre-Duel Monsters was this, doling out penalty games to the Monster of the Week bullies (occasionally to Knight Templar extremes).
Both Asuka and Ryou of Otomen have this tendency. In fact they met when Ryou was protecting a guy from bullies and Asuka decided to step in. It gets to a point where not only the school bullies, but the neighbourhood yakuza turn tail and run at the sight of Asuka.
The Straw Hat Pirates of One Piece fame are essentially an entire Badass Crew of these. They do little in the way of actual pirating and are basically just sea-faring adventurers, it's just that the "bullies" they often run across are allied in some way with the very corrupt government.
Spoofed in Haiyore! Nyarko-san: Mahiro asks Cuuko why she's in love with Nyarko despite their races being mortal enemies. She explains that in Space Preschool, the other kids talked her into playing pretend, but had her be the villain so they could beat her up. Eventually, Nyarko came in and trounced the bullies, winning Cuuko's affection. Later on Mahiro asks Nyarko if she remembers this, and she responds that all she remembers from Space Preschool is playing a "game" called Imagine Breaker where ran around beating up anyone she saw playing pretend — which included Cuuko.
Karma of Ansatsu Kyoushitsu was placed in Class E for bully-hunting the wrong bully and injuring a top honor student while helping a student with poorer grades. The Chairman at their school has some out-of-order priorities.
Heavily implied in the cause of OkumuraRin. Aside from our introduction to our hero is of him beating up a bunch of delinquents for killing/torturing pigeons, he used to always protect his younger brother Yukio and we later get a few flashbacks that show a lot of the time he got in trouble for jumping to attack others who hurt or mocked those weaker than them. This most likely plays into his choice of being an Exorcist; not much bigger of a "bully" you can get than an powerful demon who attacks and hurts the much weaker humans.
Grant Morrison: If anyone in the world's been bullied, then Superman exists to take out the bully, no matter how big or smart or armed that bully might be.
Complete with falling afoul of He Who Fights Monsters. Among other things in the early issues he dangles people out of buildings, throws them from those buildings into rivers, and choke slams Batman who was only attacking Superman at the time and demonstrably wasn't a threat to him.
In one arc of Gotham Central, the detectives re-open the unsolved cold case of the bloody bombing of the Gotham High School Hawks baseball team. One of the the theories of the detective who had been investigating the crime when it was fresh was that two nerds who had been bullied by the popular jocks had thrown a pipe bomb into the locker room as vengeance, supported by the fact that the two of them had actually stood up and cheered at the memorial service. However, the two nerds, who by now have grown up to become wealthy software tycoons, emphasize that they would never have done such a thing, especially since some of the boys on the team had been nice to them. One of the jocks had actually been an unofficial member of their computer club. They recognize the man suspected of being behind the bombing and are able to point the current detectives on the right path.
Even Steven was a short lived comic strip, from the late 90s, in the Britsh Anthology ComicThe Beano the strip involved a boy called Steven getting even with Bullies.
The titular girls of W.I.T.C.H. have a tendence to keep at bay their school's bullies. Particularly notable is Cornelia, who can occasionally scare them away with a couple words.
One issue of Iron Man focused on a group of schoolkids who dressed as their heroes, the Avengers, and who saved other kids from being picked on.
Kim Chul the titular "king of the pigs" regularly beats up multiple bullies by himself.
"My point is, when a demanding, headstrong, bully-thrashing Scottish girl rescues you, you kinda know what you're in store for."
In Ponyville Goes To The Dragons: Due to her upbringing, Cynder absolutely hates people who pick on the weak, and comes to Sweetie Belle's aid when she hears her being picked on Diamond Tiara and Silver Spoon by scaring them off. Ends up coming back to bite her in the tail when Rarity uses her threats towards them as an example of the dragons being dangerous to bring the Canterlot royal guards to Ponyville in an attempt to get rid of Ember.
In the Card Captor Sakura fic Shadow of the Dragon, Syaoran and Meiling beat up Satome and his goons in defense of their friends, with Syaoran explicitly warning Satome that if he does anything to hurt Sakura or the others, he will make sure they never find his body.
The outcasts in The Final, who lure all of the popular kids to a party so that they can drug them and torture them.
The title character of Matilda becomes an example of this after her father tells her 'bad people get punished'. She starts by playing pranks on her abusive father. Then she meets the Big Bad, Agatha Trunchbull, the sadistic headmistress of her school, and promptly directs her attacks to her.
A very violent example in Sleepers. During their time in a juvenile prison, John and Tommy were regularly beaten and sexually abused by Noakes (Kevin Bacon). Years later, after a chance encounter in a restaurant, the two men, now gangsters, violently shoot him to death
An odd accidental example in the first Spiderman film; Peter Parker manages to take out the school bully completely by accident. Well, not by accident, but he begins by accidentally activating his webbing for the first time, which latches on to the bully's lunch. When Parker panics and retreats from the lunch hall at a brisk walk, the lunch still attached, the bully of course follows him with the intention of battering Peter. Cue the bully cornering Peter against a row of lockers and fruitlessly throwing a series of punches, which Peter, with his spider-enhanced reflexes, effortlessly dodges, before Peter throws a single punch which knocks the bully on his ass! All without Peter knowing what the hell is going on!
This is one of the reasons Hanuman reincarnated into Maruti in The Return of Hanuman, especially for Minku. One time most of the students teased Maruti and Minku as they quickly become friends. Minku said that they cannot be friends because he's afraid that Maruti will also be teased if he befriended him. Maruti then got angry and lifted one of the teasing students' desk up on a ceiling fan.
Subverted in Three O'Clock High: The burly jock Craig Mattey is known for pummeling a bully, but he later admits that the bully's victim paid him to do it. The main character hires Craig's services against his own bully, but doesn't get his money's worth.
The short film Hitmen for Hire is about two hitmen who protect a student from bullies using violent means. It becomes incredibly scary when you realize who made the film — Eric Harris and Dylan Klebold, the Columbine killers.
Dick Tracy: The Kid snatches wallets and other valuables for Steve the Tramp, a hideously ugly bum who lives in a shack on the edge of town. After bringing Steve a stolen watch, the Kid tries to help himself to some of Steve's roasted chicken - and gets viciously backhanded to the floor. That's when the titular detective (whose watch the Kid stole) shows up unexpectedly, orders Steve to let the Kid have some chicken, and knocks Steve around with surprisingly powerful punches that eventually cause the entire shack to collapse (fortunately, after all three characters have cleared out). The police soon show up and arrest Steve, whom Tracy says is getting what he deserves for daring to abuse a child. (He then asks the kid if Steve is his father, but the Kid just sneers and tells Tracy to mind his own business.)
Jasmine tells Razoul to let go of Aladdin. He calls her a street mouse before throwing her down so she reveals who she is and orders him to unhand Aladdin. Later she tells Jafar, "When I am queen, I will have the power to get rid of you."
Aladdin himself stops Prince Achmed from lashing a young child with a whip early in the movie.
In Captain America: The First Avenger, Steve Rogers' motivation for wanting to join the Army and volunteering for the Super Soldier Experiment: "I don't want to kill anyone. I don't like bullies. Don't care where they are from."
In The Amazing Spider-Man (2012), Peter Parker is one of these before getting his spider-powers, despite having no fighting skill. He saves another kid from being bullied by Flash Thompson, by making himself Flash's target instead. He seems to realize what a bad idea it was right before he gets his ass kicked.
In ''Wreck-It Ralph", Ralph scares the absolute crap out of a bunch of racers who are bullying Vanellope von Schweetz. They deserved it.
Deconstructed in Angus (1995), as the young title character, who has long suffered from bullying at school, is perfectly capable of taking on Jerk Jock Rick mano-a-mano (he pretty much spent his early childhood breaking Rick's nose at least once a grade). However, that's not going to help Angus' situation outlined in the film. In fact, it never really helped him in times past.
Richard in Dead Mans Shoes goes on a hunt to take revenge for the awful things been done to his brother.
In Madeas Family Reunion, the school bully should've check to see who's the foster mother of his target and hope the title character isn't the one, which he learns the hard way.
Exaggerated with both Pamela and Jason Voorhees in the Friday the 13th series. Jason drowned due to his ignorant camp owners being busy having sex, which made Pamela go nuts and kill them both for not saving her son. However she didn't stop there, she wound up killing ANYONE that set foot in Camp Crystal Lake since it reminds her of her son's drowning. However once Pamela is killed, Jason takes over her role and carries out his mother's endless desire for revenge as well.
Alex Rider has a few examples in his limited downtime at school. One being tracking down a pair of drug dealers and using a crane to dump their lab-boat in a police station car park.
Kel in Tamora Pierce's Protector of the Small quartet. She's eventually able to persuade her peers to join her, and the victory is not that they are able to beat up the bullying pages, but that her group of people who believe it's not acceptable for older pages to torment and hurt younger ones is big enough that the bullies just stop.
The Stainless Steel Rat was bullied in school, so he bribed the PE teacher into giving him martial-arts lessons. He became hugely popular among the wimps for his ability to send entire gangs of bullies fleeing in fear.
Harry Dresden fights for the muggles who refuse to believe in the magic he fights with/against for this reason. We don't learn how core it his to his pyromaniac-wizard persona until Ghost Stories, where we finally see his fight with He Who Walks Behind.
He's so well known for this, both in combat and in making fun of said monsters, that he jokes that if he didn't make fun of a particular Eldritch Horror, they might be offended.
The plot of Past Mortem by Ben Elton is based around a detective hunting a serial killer whose victims are all bullies; initially former school bullies whom the killer finds via Friends Reunited, but then teen bullies whose victims had contacted a charity helpline.
Tobias gets into this somewhat after becoming trapped as a hawk in Animorphs, mostly because he had been repeatedly bullied as a human. He sees a couple of bullies harassing Erek King before getting to know Erek, and was about to dive bomb them when something else happened instead.
This is the premise behind Neal Shusterman's The Shadow Club.
Commando Riviera is one of these in The Twinkie Squad by Gordon Korman. He's actually quite nice, but unfortunately, he comes across to authority figures as a thug who starts fights for the heck of it.
At the start of Dinoverse Janine Farehouse has taken on a role with shades of this. Her bullies are cruel gossipers and saboteurs, rarely lowering themselves to assault. Ever since her best friend betrayed her for popularity Janine has developed a piercing stare that intimidates her peers. They can't hurt her anymore. Whenever she shows up, they change topics and forget what they were discussing before.
Adult example in Scrubs. Dr. Kelso does his absolute best to make Elliot's life a living hell. When he engages in a particularly brutal session (while Elliot was in the middle of her own personal Trauma Conga Line), Dr. Cox, the resident Jerk with a Heart of Gold, steps in and wallops Kelso so hard he has a squeak in his nose that makes him audible from a hallway away. And out of his shoes, don't forget that. He whacked him so hard his shoes stayed perfectly stationary while his feet came out of 'em.
Seth Bullock in Deadwood hints at this background. When Hearst gets on a particularly loathsome role, Bullock interrupts with barely contained rage, stating that bullies never know when to shut up. Hearst takes the hint and leaves.
MTV Show Bully Beatdown is this trope manifested, with professional mixed martial artists as the bully hunters.
Happens on Step by Step, of all shows. When the nerdy Mark is being bullied, he doesn't tell anyone about it because he's too humiliated at being beat up by a girl. When his tomboyish stepsister Al finds out about it, she confronts the bully directly and gives her some very blunt threats about what she'll do if the bully ever picks on Mark again. The bully, remembering that Al beat the crap out of the toughest male bully in the school, immediately complies.
Buffy has a habit of doing this, once pinning Larry to the wall when he was about to beat up Xander. Helps that she has Super Strength. Also saves the world.
She also gets a group persecuting witches to back down by smiling at them. The fact she is known as a pyromaniac (her old school gym), possible murderer (Ted, Kendra), borderline psychotic (thanks Cordy) or any combination of the above helps.
In a scene late in The Movie, Buffy is already in a bad mood when a lecherous male student grabs her rear end. Within seconds, she's judo-flipped him into the lockers and reduced him to a cringing coward who instantly apologizes. The other students at Hemery High just look on in shock, since Buffy has never been seen doing anything like this before.
And yet again during a self defense class when Larry the Jerk Jock is leering at a female student, and wanting to get his hands on her. Buffy bounds right up to her side and sweetly offers to be his partner instead, the implication that she will kick his ass six ways from Sunday very clear. Willow then intervenes, leaving Buffy to pout about ruining her fun.
Buffy also defends Willow whenever people attempt to pick on her.
Season seven has Buffy working as school councilor. When Amanda tells her about a abusive boyfriend Buffy says she needs to stand up for herself. Amanda replies she already did and smashed his face into the pavement, she needs advice on whether she should do it more.
The Criminal Minds episode "Elephant's Memory" had a brilliant but deeply troubled student who was the victim of truly horrific bullying hunt down and kill all of his previous tormentors. Reid, a victim of bullying, is sympathetic to him.
Considering that Reid's day job is hunting down sadistic serial killers, he probably qualifies as a bully hunter himself. Other members of the BAU like Hotch and Morgan chosed their careers as a catharsis for the abuse their suffered during their chiidhood, and Rossi's barely veiled rage toward serial killers (he wrote in one of his bestselling books that the death penalty is not about justice but revenge, and that it is a good thing) may show that the BAU Unit the show is centered on is a team of Bully Hunters who treat their job as a personal crusade
In Season Two of Glee Santana blackmails bully Karofsky into forming the Bully Whips so they can win Prom King and Queen.
Jeff Winger in Community is an odd example of this. On the surface, he's a self-involved Jerkass who is thoroughly reluctant to involve himself in anything outside his little bubble, and isn't exactly shy about shooting nasty comments at people who he doesn't like very much. However, he consistently appears to be unwilling and / or unable to let bullying go unchallenged; every time a bully or group of bullies has appeared, even if his friends aren't the direct victims (although especially if they are) Jeff has almost inevitably ended up challenging and getting into conflict with them. He'll usually frame it as challenging them for being an obnoxious, irritating dickhead rather than a bully, but it's a consistent trait of his. In one episode we learn he himself was bullied as a child, which might explain it.
In an episode of Sliders, "The Guardian," Quinn tries to coach a younger version of himself on an alternate world to stand up to school bullies, hoping to right a wrong that happened when he was a kid. Partially subverted, as it turns out Quinn's goal is not to get back at the bullies, but to prevent his younger self from permanently disabling one of them with a baseball bat. Instead he teaches the kid self-defense so he fights them with his hands.
On Judge Judy, if the case is about bullying expect Judy to make the bully break down in tears.
In Malcolm in the Middle, one episode saw Reese realize what a jerk he'd been at school and turn into a pacifist. With the alpha jerk of the schoolyard gone, the entire school goes into chaos as over a dozen bullies all vie for the empty throne left vacant, multiple bullies harassing the same kids multiple times in a row (one of them gets his shirt and shoes taken after the first bully gets his lunch money). When several of them team up on Stevie, Reese is outraged that his wheelchair immunity is being ignored and rises up to perform a bully beatdown of epic proportions.
Stephanie La Maravillosa and Keta Rush, The Bully Busters of WOW (Women Of Wrestling)
Cyrano de Bergerac: Cyrano is now an adult who undoubtedly has suffered for bullying all his life given his enormous nose, but he proclaims himself a bully hunter at Act I Scene V by challenging anyone to bully his enormous nose threatening (and dispensing) Disproportionate Retribution:
So did Asuka Kazama in Tekken. Joining the tournament is her way of going pro.
Kiyo Tsukino of Rumble! @ The Campus is a well-known one (in her school, that is).
So does Keiichi and Motoko, but the former is a bit of a coward and the latter is unaware of being one.
Antimony of Gunnerkrigg Court delivers a beautiful display of the trope when she takes down the class bully who was tormenting Kat. It cements their friendship.
Overlaps with Did You Just Flip Off Cthulhu? at one point. When Coyote starts insulting Ysengrin at a meeting he specifically asked for with Antimony, Antimony calls him out on it and starts to leave the forest.
The unnamed title character of The Bully's Bully. She is a Martial Pacifist who tries her best to stop bullies from tormenting the helpless, and tries her best to settle things without violence, but is not afraid to kick ass when that fails. She also has a Sixth Sense in regards to people being bullied in general.
In Xin, the eponymous character basically make this his "hobby", second only to his overall goal of reforming the corrupt school system.
In The Simpsons episode "Bart the General", Bart doesn't just go bully hunting, he does it on a grand scale with the entire class ganging up on Nelson and his gang, complete with aid from Grandpa and Herman. He even goes far enough to get Nelson to sign a treaty saying he "respects Bart's right to exist."
The trope is even explicitly invoked in an earlier scene, when Bart angrily confronts a Mook who has stolen his sister Lisa's cupcake. Despite Lisa trying to warn him that the Mook works for Nelson, Bart tries to pummel the thug into submission, gets hauled off the floor, throws a wild punch without looking - and soon discovers that he has swung right at Nelson's face, bloodying it! Once Nelson realizes that it's his own blood he's tasting and not that of a victim, he immediately burns with hatred for Bart and warns him that he's now as good as dead. But Lisa is proud of her brother for being so brave, and points him out to the entire school as "Bart the Bully-Killer" - a moniker that Bart would just as soon not have.
Poindexter, the ghost of a bullied nerdy teen who lived in the 50's, in Danny Phantom, who now as a ghost targets him when he thinks Danny is bullying Jerk Jock Dash Baxter.
An episode of Fillmore! had the safety patrol tracking down someone targeting bullies for humiliation, ending with An Aesop about there being better ways to deal with bullies.
A cut scene from So The Drama has Kim Possible comment that she could beat up on the Alpha Bitch, but doing that is beneath her. Still, she teaches sensitivity training to boys picking on Ron and as a four year old beat up pre K versions of Drakken, Killigan, and Monkey Fist. The one time it looked like she had been pushed to the point of attacking Bonnie, it ended up with Bonnie breaking down crying at the prospect of Kim justifiably thrashing her.
On American Dad!, Stan starts bullying Steve in an attempt to make the boy more assertive. After weeks of being beaten senseless, Steve does learn a lesson on taking action for himself, but not the one Stan hoped. Steve hires Stelio Kantos, Stan's former high school bully, off of Facebook to beat the ever living daylights out of Stan until he agrees to leave him alone.
Deconstructed on an episode of Family Guy: Peter enlists Chris's help in scheming against a bully who had tormented him many years ago; the former bully is now a reasonable adult who doesn't really remember what he used to do as a kid. When they finally track the guy down, Peter threatens and taunts the other guy before ordering Chris to take him out. And then Chris....beats the living snot out of Peter, driving him to tears. Peter demands to know why his son has beat him. Chris replies, in a Crowning Moment Of Awesome, that "you taught me to stand up to a bully - and I'm standing up to you."
Just so this makes sense to those who don't understand, Chris was being bullied by this kid who was stealing customers from his paper round, insulted and humiliated him, etc. When Peter confronted the little punk, the kid starts insulting and cracking jokes about Peter, a fully grown man whogets into a glorious fist fight with a giant chicken, when he was trying to be civil, resulting in Peter beating him into unconsciousness. When he apologizes, the kid convinces him that its fun to hurt people, so Peter started bullying everyone, from his family to his friends to his paraphelgic cop neighbor. He decided to hunt down his own former tormentor when he realized it was his fault for why he was acting so dickish, only to find out he now has MS and is unable to walk by himself. Peter doesn't know what that is (confusing it for a Monkey Scrotum), and attacks the man on crutches so Chris beats him up to stop him.
In another episode, Peter tracks down Connie D' Mico, Meg's Alpha Bitch high school bully, and smashes her face repeatedly through a fire extinguisher.
The first episode of X-Men: Evolution establishes Scott as this, and the bulk of his rivalry with Jerk Jock Duncan is motivated out of Duncan's casual bullying (the rest is because Duncan is dating Jean, Scott's best friend and eventual love), while his intense dislike of the Brotherhood comes down to their tendency to act like jerks to people. Later episodes give this trait to just about everyone once mutants are revealed (Thought understandable since its, you know, them who're being picked on). Special note should go to Rogue, who on two different occasions drives off bullies harassing one of her teammates because of their mutant status (first Scott, with the help of Kitty, though as Scott showed a few seconds ago, he didn't need it, and secondly Evan, who also didn't need it but needed someone to drive them off before he did something stupid).
In ThunderCats (2011), CatfolkRebel Prince Lion-O gradually becomes this, as he disapproves of Thundera's Fantastic Racism and sometimes sticks up for other species. This tends to get him in trouble, first attracting the ire of several thugs in the slums of Thundera after he witnesses them beating up a Dog, then almost getting killed by an Angry Mob after he tried to defend a pair of captured Lizards from them. He eventually actively engages in bully hunting, taking up a predatory Master Swordsman's challenge in hopes of defeating him.
Bugs Bunny tended to be a fairly good-natured fellow who didn't actually seek out bullies, but if he was provoked, or if he saw it happening, he'd take it upon himself to put a stop to it. In fact, they even had to create a new character to avert the He Who Fights Monsters danger the trope often runs into; though Elmer Fudd versus Bugs Bunny is an iconic rivalry, the factors that made it famous meant that there were actually very few Bugs vs. Elmer cartoons: Bugs is simply so much smarter than his would-be murderer that Elmer's threat is completely defused and Bugs starts to look like the bully. So they created Yosemite Sam, who was (relatively speaking) much smarter than Elmer, and far more belligerent, so that Bugs could have someone to face off against who wouldn't take too much audience sympathy from Bugs. Yosemite Sam, however, had started gaining audience sympathy as he was never seen doing any actual bullying (just boasting and grandstanding), and Marvin the Martian was created to face Bugs, whose threat was actually shown onscreen and never underwent Badass Decay.
The Bugs Bunny cartoon "Rabbit's Kin" plays this trope perfectly; when a frightened baby rabbit ducks into Bugs' hole to evade Pete Puma, Bugs rallies to the young rabbit's defense.
In the Tom and Jerry cartoon "Neapolitan Mouse", while Tom pursues Jerry through the streets of Naples, an Italian mouse beats up Tom, clearly upset to see a big mean cat picking on a little mouse. He then takes down some mean dogs that were harassing Tom, for much the same reasons.
Rainbow Dash will stick up for others if they're being picked on. For example, in flight camp she defended Fluttershy from a trio of bullies, after the latter tripped while trying to fly through a cloud ring.
The aesop of "One Bad Apple" was that one should stand up to, and otherwise deal with, bullies without stooping to their level. It failed abysmally, instead implying that fighting back made you as bad as the bully.
Various characters of Thomas the Tank Engine are played this way if Laser-Guided Karma doesn't catch up to the rude and mean engines. Whenever there's a engine who is usually big and orders others around, there will be another engine to help the victim in playing tricks on the teasing engines (i.e. Duck helped Percy to get back at Gordon, Henry, and James for ordering them around in "Duck Takes Charge"). The Troublesome Trucks aren't safe from these engines either as they would mostly be in the receiving end of being bumped or broken if they tease the other engines (i.e. S.C. Ruffey in "Toad Stands By").
The only reason the violent, foul-tempered Dinobots of The Transformers are loyal to the Autobots is that the only thing they hate more than weaklings are those who abuse their strength.
The Batman Beyond episode "Payback" features a masked Vigilante Man who specifically targets adults (parents/teachers/bosses) that bully various teenagers in Gotham City. It is revealed that Payback is the son of a doctor at a local youth counseling center, who was depressed that his father was spending too much time counseling other teenagers and neglecting him.