One of the assassination jobs in Noir was because of reasons like this. The girls were hired to kill a man who had run a concentration camp responsible for the slaughter of an ethnic group in Eastern Europe. The survivors and their descendants hired Noir to kill him in revenge. As the episode unfolded, they find out that the man had not only become the kind and benevolent benefactor of a poor community, his own people had been slaughtered by the aforementioned ethnic group as part of an ongoing blood feud when he was a child.
In Elfen Lied, you can understand both sides. But they are also both wrong. At the point of the manga, it has become "kill or be killed" for both sides. For instance, Lucy is driven to her acts through cruel and depraved treatment, but after killing the horrible people, she kills innocents as well, and infects others who survive their encounters with her. Infectees ended up with their children being born silpelits, and in turn, the silpelits kill their families as well, so they sign up to suppress the diclonius virus, causing many inhuman experiments. The experiments break out and kill the scientists and several innocents so the military puts them down. Kurama was infected by a silpelit, and loses his wife in child-birth, he seemingly kills Lucy's only friend, and captures her, so she maims his adopted daughter and kills his biological one. He accidentally shoots Kouta, and she rips his arm off.
Bloodshed begets bloodshed. Hatred begets hatred. The rage and emotion sinks into the land and stains it with the crest of blood. No matter how many times they repeat themselves, they never learn. These sad fools...
It is also averted with Winry deciding to spare Scar, who killed her parents. Since Scar is all about the vengeance - and expanding, not shrinking, its scope - he is mystified and possibly mellowed by Winry's kindness in the face of the wrongs he did to her.
In Naruto, revenge is one of the main themes. The one who is biggest on revenge is Uchiha Sasuke, who is trying to avenge his family, who were killed by his brother Itachi, going to all possible extents to reach this goal. Until he discovers that Itachi was forced to do this to save Konoha, because his family tried to get revenge on the others in the village for being treated as outsiders and for them casting out their leader. Who, by the way, also wants revenge for his clan not supporting him and assists in their murder. And then Sasuke wants to get revenge on Konoha... Just as Kakashi told him once: revenge just leads to new revenge.
The entire Uchiha versus Senju issue actually appears to have a consistent pattern to it with the big names. It began when the eldest son of the Sage refused to accept his younger brother being heir, splintering their family permanently. It repeated again when Madara refused to accept Hashirama as the First Hokage, cementing the rift between the Uchiha and Konoha, as a Senju was its first leader. And now it is repeating with Sasuke refusing to accept Naruto could grow so much stronger than him, driving him to Orochimaru and Madara.
This is Pain's entire theme — trying to create a weapon so strong it'll stagnate the cycle due to fear. He uses it for many a Not So Different speech as well. Naruto ultimately decides to break the cycle of revenge between Pain and Konoha by sparing him. This pays offtremendously.
Sasuke himself came close to potentially starting one between his team and some members of the Cloud village by apparently killing Killer Bee, with the fact that he actually failed to capture him making revenge extra-pointless. Naruto, seeing where this would end up, decides he needs to do whatever he can to stop this.
In an interesting twist, Shikamaru cites this as his reason for wanting Konoha to kill Sasuke. So that Sakura and Ino won't go out to avenge him if the Cloud ninja kill him, which would result in them being killed and avenged by their loved ones, creating a vicious cycle that would lead to war.
Revenge is often used in the Gundam franchise. Especially various Char Clones (tm) are often motivated by it. Char himself and Zechs Marquise try to avenge the murder of their families, therefore infiltrating the responsible military organization. Lockon Stratos goes to all possible extremes to avenge the murder of his family. Flit Asuno even goes to the point of becoming a Dark Messiah because of his desire to avenge his parents as well as YurinL'Ciel.
This is given the most emphasis in Mobile Suit Gundam SEED, after the Atlantic Federation (secretly ruled by Blue Cosmos) destroyed a colony of PLANT, ZAFT quickly invaded wanting revenge, with the brunt of this by Patrick Zala whose wife was killed during the attack. After Blue Cosmos gains control of the entire Earth Federation, and Patrick Zala gains control of PLANT the war becomes one of genocide as both forces seek to completely annihilate the others. Patrick Zala having been driven insane by the death of his wife is finally killed before he can kill the Naturals.
Mobile Suit Gundam SEED Destiny continues the Blood Feuds, with Radical Coordinators who were followers of Patrick Zala dropping the remnants of the colony on the Earth as they believed that the Earth peoples' (naturals) haven't suffered enough in the war, believing that they deserve to die for Junius Seven. The people who dropped that colony seem to have lost family and friends in that attack. The violence feeds into each other, and the Earth peoples reignite their hatred at the Coordinators and declare a second war against ZAFT.
Cagalli sums it up quite nicely.
Cagalli Yula Athha: "One guy's killed for killing another and then he's killed for killing him. How is that kind of twisted thinking ever gonna bring us peace? Well?"
This is the purpose of Zero Requiem in Code Geass. Unlike many of the examples in this list, the idea is that if Lelouch is hated by everyone, then dies with no one to avenge him, then the cycle will end. This has not really gone well with a large portion of the fanbase, as there are far too many things that Lelouch was never responsible for, and fails to exonerate Britannia in the eyes of it's many victims, nor does it really provide a solution to Britannia's massive racism problems.
A continuing theme in Gunslinger Girl. Both Agency handlers and terrorists are obsessed with avenging family members killed by the other side. Those who aren't are invariably either corrupt leaders or disillusioned veterans.
Used in the otherwise nonsensical filler-filled third season of Zero no Tsukaima. The audience expected that The Atoner Colbert had died due to injuries in season two, but some Ass Pull revived him. This gives Agnes a good reason to kill him. But then she gave a reason not to: if she killed him in revenge and cold blood, his students would avenge him, perpetuating the cycle of hatred and revenge. It is hinted that she will still kill him, but presumably in a fair, no-hard-feelings kind of duel to the death.
Afro Samurai has this as the main theme of the series. Sure, you can get the title of being the number one fighter, but you have to take lives to do so. Which won't sit well with the surviving kin/friends of the deceased, as Afro roughly finds out.
At the end of Resurrection, Afro has come to accept this. On reclaiming the Number One headband, he goes to a child whose adoptive father Afro killed in front of him - the same way Afro's father was killed in front of him - and hands him the Number Two headband, with a quiet, "Any time you're ready".
The major plot line in the 2nd season of Hell Girl.
As well as Ren, Iron Maiden Jeanne, Lyserg and the rest of the X-Laws, and a number of others. The Arc Words in the Kyoto Island arc are "When you hurt people, they hurt you back."
A central premise in Studio Gonzo's Romeo X Juliet, where it's strongly implied that the love between the eponymous protagonists is the only thing that can prevent the cycle of violence from continuing (and that the fact that one started in the first place may very well cause The End of the World as We Know It).
A horribly convoluted one in Master of Martial Hearts. a generation ago Aya's father organized a Street Fighter expy brawl for plucky Action Girls. Aya's mother won, the other contestants were mindraped to the breaking point, conditioned into sexual slavery and sold. Two sisters in particular took the short stick: the younger got raped and killed by Aya's father, in front of her young daughter, Miko, the eldest got her voice box removed and was sold overseas. She managed to escape, rebuilt her life as a somewhat functional Stepford SmilerCute Mute and had a daughter, Natsume. When the two cousins managed to know all the story, they decided to exact revenge. By masterminding and creating a new Platonic Hearts Tournament. And enrolling Aya. And making her fight, and defeat, countless otherwise innocent Action Girls. Who are then promptly mindraped and maimed as their mothers were.And trying, failing, to get Aya to suffer the same fate.. Casting aside the sheer idiocy of the whole plan, there's no warranty whatsoever that the cycle can't be restarted at any time, now, something Aya is willing to change at the end of the series even if it means having to murder Natsume and Miko's families so they don't start any more trouble.
Averted in One Piece. It began when Usopp was beaten up by the Franky Family as they stole the crew's money. Cue the Straw Hats retaliating by destroying the Franky Family's home with everyone in it. When Franky finds out his nakama were beaten up and their home in pieces, he says This Is Unforgivable and hunts Luffy down to get even. However, a series of circumstances would have the Straw Hats and the Franky Family work together and in the end, Franky pulled a Heel-Face Turn and ended up joining the Straw Hats.
The Fishmen Island arc is all about this, bringing together several subplots that have been running since the beginning of the series. Queen Otohime is the most open-minded of the fishmen/mermaids and advocating for peaceful reconciliation rather than continued retaliation against humans, which she would hold even to her death and pass on to her children.
Arlong, while initially not as willing to kill and subjugate humans as seen in his flashbacks, let his continued hatred and prejudice (as well as his captain Fisher Tiger's death by humans) convince him that all humans are nothing but trash. His actions encouraged Hody Jones, who had grown up in a culture dominated by hate and racism towards humans and sees anyone associating with humans as his enemy, attacking and killing fishmen/mermaids. Hody Jones was the one who killed Queen Otohime and has even stated that humans have done nothing to him personally.
Averted in Code:Breaker: Kouji allowed Toki to believe he was the one who killed Nenene so that Toki wouldn't kill the real murderer Saechika, causing the Prince to kill Toki to avenge her long-lost brother. "I killed your sister and your brother is dead. Things are neater that way."
Averted in Heartcatch Pretty Cure. After Dune kills Yuri's father, Yuri's on the verge of tearing him apart. However, Tsubomi, who witnessed the action as well, stops her and begs her not to go through with it. It works and the later-united team is able to put Dune down properly.
In the original Teenage Mutant Ninja Turtles comic books, the turtles kill Oroku Saki/The Shredder on Splinter's behalf, as revenge for the death of Splinter's former owner, Hamato Yoshi, who had died at Saki's hand. Yoshi, for his part, had been killed (along with his lover Tang Shen because Saki was a dick) as revenge for slaying Oroku Nagi, Saki's older brother. Why was Nagi killed? Because when Tang Shen, the object of both Yoshi and Nagi's affections, chose Yoshi over Nagi, Nagi flew into a rage and savagely beat her; one berserker rage later, Yoshi had killed Nagi. Saki's death wasn't the end of things, however; after he was slain, the Foot Clan that he led became honor-bound to kill the turtles in order to avenge him, and the cycle continues until Karai, who had been sent from Japan in order to unify the then-warring Foot Clan, offers to end the vendetta if the turtles help her eliminate one of the rogue factions, a deal which they take.
In a sort of one-sided variation, old DC Comics villain/antihero The Shade keeps being pursued by the descendants of a criminal he killed over a century ago.
Scion was built on this trope. The Heron and Raven kingdoms fought each other for centuries without even remembering why before settling their differences by Combat by Champion. Ethan accidentally cutting Bron's face in a combat tournament leads to Bron taking Ethan under custody, which leads to Ethan escaping, which leads to the Ravens declaring war on the Herons, which leads to Bron murdering Ethan's brother Artor in battle, which leads to Ethan going after Bron, and so on and so on until the Ravens and Herons unite against the invading Tigris kingdom.
This is the concept of Jango Fett's backstory comic series. It progresses thusly: Vizsla murders 10-year-old Jango's family. Jango helps the Mandalorians kill all of Vizsla's men and horribly scars his face. Vizsla leads the Mandalorians into a death trap and personally kills Fett's Mandalorian mentor. Vizsla frames the Mandalorians for mass murder and the Jedi kill all of them. Fett destroys Vizsla's ship, killing most of his men and savagely beats him down (though he gets a nasty beating in return). The cycle is ended when Fett slashes open Vizsla's belly, causing him to be set upon by a pack of predatory cats while Fett plays dead.
In Kill Bill, The Bride gets revenge on Vernita Green for having a hand in the massacre of her wedding party. But after killing her, The Bride realizes that Vernita's daughter, Nikki, had witnessed the whole thing and so The Bride says to Nikki, "When you grow up, if you still feel raw about it, I'll be waiting." Tarantino has said that he's interested in making a Kill Bill Vol. 3 in the future, where a grown-up Nikki Green hunts down The Bride, and a fourth film that elevates into this with B.B. (Bill & The Bride's daughter) hunting down Nikki for killing her mother.
"There's a little something called the law of reciprocity. You kill one of theirs, and they kill one of ours. Here's a piece of general advice: if you're going to kill one, make sure you bloody well kill them all."
In City of God, the gang war is touched off by revenge against Lil Ze for raping Knockout Ned's girlfriend and killing his brother and uncle. However, in a year, no one knows how it started, as everyone joins sides for revenge on the other side.
With the notable exception of the kid who kills Ned. He had joined NED'S side, telling them he wants to get revenge for his father's death. Turns out he was the son of the security guard that Ned killed near the beginning of the war.
In Death Sentence, Nick (Kevin Bacon's character) having his son killed in a gang initiation, which leads to Nick killing the guy who killed his son, which leads to the killers coming after him, which leads to Nick killing one of the killers, which leads to the killers killing Nick's wife, which leads to Nick killing the rest of the killers.
This is the entire basis of the film Changing Lanes: When each man refuses to budge and try to see things from the other person's shoes, they get stuck in a cycle of increasingly undiplomatic responses and revenge. Throughout the film, it is shown where each gets opportunities to end it by doing the right thing... opportunities that are, for the most part, promptly ignored.
Discussed in Troy. Hector kills Patroclus in battle, so Achilles kills Hector, so Paris plans to kill Achilles. Briseis asks Achilles where it all ends, and he replies "It never ends".
The Joshuu Sasori films develop a series of these across the first 4 entries. The protagonist's desire for revenge against the detective by whom she was seduced and betrayed fuels her repeated escape attempts. Thus, the guards hate her. This results in harsh punishments for all the prison inmates, which means they all hate her too, and they hate the guards almost as much. The warden hates her personally for causing all the trouble, and for the pain and embarrassment she's caused to happen to him personally. In the 2nd film, savage new inmate Oba sees her as a threat to her dominance among the prisoners, causing more betrayal down the line, and a new vendetta for Matsu. The 3rd film replaces the guards with detective Kondo, who takes her escape understandably personally. There's also the jealous woman downstairs from her, and old enemy Katsu to deal with. By the 4th film, every policeman and member of prison staff hates her passionately.
Claus: "If you hit him, then he hits you, and then it never ends!" Christian: "Not if you hit hard enough the first time."
Of course Christian's worldview does come back to bite him hard, when he accidentally injures his best friend during another payback mission.
Casper Meets Wendy: Desmond Spellman wanted to kill Wendy to prevent her from becoming more powerful than him as predicted at a prophecy and, to make sure nobody would try to avenge her, he intended to kill her family.
In Taken, Bryan slaughters the members of a human trafficking ring, including one named Marko, to rescue his daughter. In Taken 2, the villains' families, lead by Marko's father Murad, attempt to avenge them and attack Bryan and his family. Bryan attempts to end the cycle by sparing the life of Murad, but the man tries to kill him and Bryan kills him. Murad had two other sons..
Such a cycle between the settlers and the Eora is portrayed in The Secret River.
Discussed or played straight several times in Beowulf: The "Finnsburgh fragment" is a Nested Story about a feud between Jutes and Frisians, Beowulf himself predicts that peace between Danes and Heathobards will not be lasting because of this, and a subplot revolves around the traditional enmity of Geats and Swedes.
Edgar Allan Poe's short story "Metzengerstein", in which two noble families have a perpetual feud based on this (and on an ambiguous prophecy). Ends with the last scion of Metzengerstein killed by a horse inhabited by the spirit of the lord of the other house, who apparently died in a fire the Metzengerstein heir started. Naturally, these events also fulfill the prophecy.
A Series of Unfortunate Events. The Baudelaires spend much of the series trying to bring down Count Olaf, who continuously attempts to steal their fortune and is implied to have killed their parents. It is later strongly implied that the Baudelaires' parents had previously killed Count Olaf's parents.
In Dan Abnett's Gaunt's Ghosts novel First & Only, when the Jantine Patricians raid the Ghosts, Gaunt sends Corbec off to raid them back. When discussing what to do, Corbec declares that they should kill as many Jantines as Ghosts who died — at least. (On the other hand, both raids had been part of a cover for deeper games, and part of the raid was to feed that cover, making it look like Revenge.)
Also in that book, the reason that the Jantine/Tanith feud had started in the first place was that years before Gaunt took command of the Ghosts, he had executed the Jantine Colonel's father for desertion in the heat of battle, which had led to the death of Gaunt's father.
The biblical story of Samson, from the Book of Judges, consists mainly of a Cycle of Revenge: At one point, within a few verses, a Philistine commander claims "We just want to do to him what he did to us" and Samson claims "I just want to do to them what they did to me."
A recurring footnote in any Discworld book discussing Dwarf/Troll relations explains that war cries such as "Remember Koom Valley!" all tend to translate to "Let us remember the atrocity committed against us in the past that will excuse the atrocity we are about to commit today!" Thud!! in particular focuses on this theme, and particularly on an attempt at breaking the cycle. At its very beginning.
The Corsican Brothers (The original, not the Cheech and Chong lampoon!).
In Nick Kyme's Warhammer 40,000 novel Salamander, in the Back Story, the 3rd Company had killed some renegades' captains; in the opening, they kill the 3rd Company's captain; shortly thereafter, the new captain goes in pursuit of them. They get sidetracked by another issue, but happen on the killers, and get both the commander and the actual killer. Whereupon their captain is murdered after the battle.
And his white hair sank to his heels, and his white beard fell to his feet, And he spake to me, 'O Maeldune, let be this purpose of thine! Remember the words of the Lord when he told us, "Vengeance is mine!" His fathers have slain thy fathers in war or in single strife. Thy fathers have slain his fathers, each taken a life for a life, Thy father had slain his father, how long shall the murder last? Go back to the Isle of Finn and suffer the Past to be Past.'
In Harry Turtledove's Timeline-191, the Confederacy wins the Civil War and then, with help from Britain and France, defeats the USA in another war twenty years later. This leads to a culture of "Rememberance" and revanchism in the USA, who plan for victory in another war and make an alliance with Germany for that purpose. This comes during the Great War, when the USA soundly defeats the Confederates, who then embark on an even more brutal program of revanchism and preparing for the next war under Jake Featherston's Freedom Party. If this all sounds familiar, it's because the series is largely based off of European history (see the Real Life section below) moved to North America.
The hat of the Arends in the Belgariad. Polgara nearly falls into it herself in the prequel novel, but is strongly encouraged not to by her mother.
The In Death series: The book Vengeance in Death is all about this trope. Roarke murdered six men to avenge the death of Summerset's daughter. Then the wife of one of the six men raises her son to murder six people who helped Roarke hunt down the six men, as well as Summerset, Eve, and Roarke to make a novena. Just goes to show Revenge has a lot of nasty consequences!
Age of Fire: A recurring theme throughout the series, but especially highlighted in Dragon Avenger. Wistala eventually tries to end this in regards to the Dragonblade line by making peace with the current one and his family, rather than take revenge on him for killing her father.
By the time of the first Dune novel, the Atreides and Harkonnen families had been feuding for millenia, and the feud only ended with the death of Feyd, Rabban and Vladimir (The last surviving members of the Harkonnen family, not counting Vladimir's unacknowledged daughter Jessica and her Atreides descendants) at the end of the book. The feud apparently started because at some point thousands of years earlier, an Atreides general had reprimanded a Harkonnen subordinate for botching an assignment (Something which is normally considered acceptable behavior for a senior officer when someone under his command screws up).
Awareness of this trope, and a desire to avert it, is the reason beyond a particularly unsavory aspect of A Brother's Price. Families tend to be tightly knit and very collective. It would be easy for a family caught committing treason to pin it on one sister, who would be executed and leave the others alive and wanting vengeance. So, unless it's believed that this was not a proper family and sisters were not united - as happened to the Whistlers well before the story's start - the whole family is killed. Right down to the babies. Men - and Princess Ren - hate this practice and it's well established that Children Are Innocent of their parents' crimes, but it's seen as ruthlessly pragmatic.
"Face the truth, Ren. She's the incestuous fruit of the man who poisoned the Prince Consort and the woman who blew up half the royal princesses! Do you think any of even her most remote noble relations are going to take her? Do you think we're going to take her? You would ask our youngest to be raised with her? Her father murdered ours. Do you think our babies would be safe around her once she realized that we executed her mothers and grandmothers? [...] Kij and Keifer had no good reason to hate you and me, except for deeds of our grandmothers. Do you really want their child, with better reasons for hating us, anywhere near our children?"
The descendents of the surviving Whistlers bear no grudge against the crowns, and in fact some of them died fighting for the same people who executed their Mother Elder. They adopt a traitor's child out of the charitable belief that there is redemption for the innocent.
The planet Melida/Daan in Jedi Apprentice has been split between the Melida and the Daan, who for many generations have been feuding over an original cause no one remembers - now each fights to punish the other for their most recent atrocity. All resources now go into fighting and memorials featuring recordings of the dead, urging the living to avenge them. The Young - the youngest generation - is sick of it.
Nim Drovis (appearing in Planet of Twilight) has been in a civil war between the Drovians and Gopso'o for nobody-even-knows-how-long. According to legend, the civil war started from an argument about whether "truth" was singular or plural, but the combatants don't really care anymore.
In Greek Ninja, it turns out to be the reason of everything that happened.
While this trope is usually pretty dark in itself, A Song of Ice and Fire manages to make itself even darker through the repeated aversions this trope; simply wiping out the entire family line of your opponents, including the children. Tywin Lannister is fond of this technique.
Prince Doran Martell of Dorne also plots the downfall of the new monarchy as his sister, Elia Martell, was raped and murdered, along with her children, for being the wife of Rhaegar.
Live Action TV
The Brady Bunch: "My Sister, Benedict Arnold" saw Greg and Marcia exercise this trope by bringing home dates deliberately picked out to annoy the other sibling. Mike and Carol make sure that neither Greg nor Marcia come out the winner, very bluntly pointing out that such behavior is unacceptable and makes them apologize not only to each other but to their "dates" as well.
The Judge: An episode of this 1980s courtroom TV series had a cycle of revenge story, where three college-aged students – two women and a man – raped each other in retribution for a previous rape one of them had committed against the other. Judge Franklin was so angry by the series of events he scolded them instead and refused to use his cheery "Be good to each other!" CatchPhrase, instead telling them to get out of his courtroom and warning that if he ever saw them again in his courtroom, they would go to jail.
In one episode of Hustle, the gang were hired by a guy's ex-wife to ruin his life because she painted a very unsympathetic picture of him, but as the episode progresses, it is really blurred as to which of them is more at fault.
An episode of Kung Fu, appropriately titled "An Eye for an Eye", focuses on this situation.
The classic Doctor Who serial The Caves of Androzani. The psychotic Sharaz Jek plunges the Androzani system into a costly war for the sole purpose of getting revenge on the business partner who betrayed and permanently disfigured him. General Chellak, on the other hand, is willing to sacrifice virtually his entire force in a suicidal frontal assault against Jek's killer androids in order to kill Jek.
The cycle of revenge has emerged as the driving force in the overarching mythology of the new Battlestar Galactica. "All this has happened before and all this will happen again."
The closing episodes of the Filipino soap opera Kung Tayo'y Magkakalayo (English: "If We Were To Be Apart") deal with this, which involves Robbie Castillo, as he is engaged in a Mexican Standoff with Ringo Quijano, who's also Robbie's brother-in-law through his marriage with Gwen.
One of the themes of Power Rangers Time Force. Ransik, the Big Bad, is a mutant driven to madness and violence by human hatred (supposedly, it's never shown and other characters claim that he was offered help), and he himself is responsible for causing both Time Force leader Jen and his own DragonFrax to hate him with a passion. The cycle ends when Ransik's daughter realizes that it's happening, and puts herself in mortal danger by going into the crossfire to convince him to let go of the vendetta. Ransik turns himself in, Jen accepts it, and Frax... well, Ransik already did him in by then, but he at least had time to reflect that his thirst for vengeance ruined him.
Power Rangers Wild Force has it at one point when Master Org is revealed to be Dr. Adler, a human scientist who became bitter because Cole's father married his mother before he could. He became so consumed by hate, he ate the remains of the original Master Org and brutally murdered them. When Cole finally defeats Master Org, reducing him to a helpless mortal man, he refuses to finish him off because he can see how Adler's hatred consumed him.
One of these becomes a plot point late in the seventh season of NCIS. A Mexican drug lord killed Gibbs' wife and daughter. Gibbs, being a scout sniper, killed the drug lord. Almost two decades later, the drug lord's son and daughter have taken over their dad's business and start taking revenge against Gibbs, threatening his team, his dad, and his mother-in-law, shooting off a finger from his mentor and killing another NCIS agent. Gibbs settles it (at least temporarily) by tricking the son into killing the daughter.
One case on New Tricks had the murder victim go to great lengths to break the cycle. A long running blood feud caused him to kill the patriarch of the other family so he fled to Britain, changed his name and went so far as to have his sister (his only remaining relative) be adopted by a British couple so she knows nothing of her heritage. He is killed but this finally ends the cycle.
This is a central theme on Merlin. King Uther is a Knight Templar who has genocided all the magic users he can find. In retribution, quite a few magicians go overboard in their attack on him, attacking innocent civilians. Thus, Prince Arthur grows up being told that magic is evil and having it constantly proven to him. The eponymous Merlin, Arthur's manservant, best friend and secretly a warlock spends most of the series trying to convince Arthur to accept magic and therefore break the cycle, but his success has been limited.
Bones: A Victim of the Week was the head of a Feuding Family not unlike the Hatfields and the McCoys. It all started when a man from one of the families and a woman from the other one were romantically involved and the two of them were poisoned. Each family blamed the other one. When the Victim of the Week figured out neither half of the couple was at fault, he tried to put an end to the feud but his attorney/daughter-in-law killed him to continue making money off the lawsuits. (In modern times, the families resorted to suing instead of murdering)
On The Americans the Soviet and American intelligence agencies end up in one after a rogue faction of the KGB hire an assassin to kill some American rocket scientists. Philip and Elizabet are able to stop the assassin but not before three FBI agents are killed in a bombing. A group within the FBI decides to retaliate by kidnapping the Soviet KGB Rezident but end up kidnapping a low level flunky instead. It seems like the feud might end right there but then Philip kills an FBI agent that is about to expose his cover. The FBI kills the kidnapped Russian and the CIA retaliates by killing a number of ranking KGB officials. The Soviet government declines to retaliate in the hope to end the pointless feud. However, Elizabeth and Claudia were very close to one of the killed KGB officers and disobey orders when they target a CIA deputy director who was involved in planning the assassinations.
Played straight in "Murder Go Round" by Insane Clown Posse, which, contrary to popular belief, clearly isn't about a ride. It tells the story of a young hoodlum (played by Violent J) who is assaulted by a gang member, and decides to get him back, starting a gang of his own and killing his enemy and anybody who tries to avenge him. Eventually, he just starts killing people for the hell of it, including his best friend. It finally escalates to a gang war in which the hoodlum (running a street gang "fifty-five strong" and completely full of himself) is shot "twice in the forehead, twice in the back" and "twice in the eye", and only realizing in his dying moments how stupid and childish the whole endeavor was.
Irishman Tommy Sands' song "There Were Roses" is based on a true incident experienced by the author. A Protestant was murdered, and a Catholic was killed in retaliation. The two had been close friends.
The Performance Video for Week End by X Japan is this, combined with Bolivian Army Ending and Everybody's Dead, Dave - everyone dies in a chain of murders and suicides, all connected to the deaths preceding them. Yoshiki's wordplay about the "end of a life" being "the end of the world" in the lyrics matches this as well - the end of the life is the end of that person's world, and if the Cycle of Revenge kicks in, a chain of murder and suicide only grows and expands...
The Oresteia by Aeschylus was written in response to this legend. It concludes with Orestes and Athena breaking the cycle once and for all by inventing the trial by jury.
Orestes nearly gets killed because he murdered his mother.
...whom he only killed because she had murdered his father, King Agamemnon.
...whom she had only killed because Agamemnon had sacrificed their daughter (Orestes's sister), Iphigenia.
...whom he only sacrificed because the goddess Artemis demanded it of him.
...and she only demanded it of him after he killed a deer in a sacred grove and boasted he was the better hunter.
As usual with Greek myths, there are actually several explanations why Artemis demanded Iphigenia's sacrifice, including one that was because Agamemnon's father had failed to sacrifice the first lamb of his flock to her, while according to Aischylos it was because two eagles (who symbolized Agamemnon and his brother Menelaos) had torn a pregnant hare to pieces, which enraged the goddess. And in the Iliad, Iphigenia wasn't sacrificed at all (Agamemnon offers the hands of all his three daughters in marriage to Achilles), while according to Euripides she was saved at the last moment and transported to Tauris (on the Crimea) to become a priestess at the local temple to Artemis...
The story is further complicated by Klytaimnestra (Agamemnon's queen) hooking up with Aigisthos, murderer of Agamemnon's father Atreus, who wanted to get revenge on Agamemnon for driving his father Thyestes (Atreus' brother) into exile from Mycene. (Because of an oracle, Thyestes had fathered Aigisthos by raping his own daughter Pelopia, in order to avenge his other children whom Atreus had killed). Aigisthos and Klytaemnestra together killed Agamemnon and Klytaemnestra for good measure also killed Agamemnon's prisoner/concubine Cassandra of Troy.
And all that came about from a curse on the House of Atreus from a man named Myrtilus, who Pelops killed after Myrtilus helped him murder King Oenomaus and marry his daughter Hippodameia to seize his kingdom. Granted, Myrtilus tried to rape Hippodameia, but Pelops still reneged on his promise to give Myrtilus half the kingdom.
Going back even further, it's been suggested that part of the curse on Pelops and his descendants comes from the hubris of his father Tantalos, who originally murdered Pelops and tried to serve him in a stew to the gods. And then there was the fact that Tantalos had stolen the food of the gods and given it to his friends, along with telling them the gods' secrets. Disproportionate Retribution much?
In Warhammer, the Dwarfs are in one of these as their natural state. In fact, they're capable of maintaining one without the other party trying to continue it. It works like this: someone does something to wrong them, so they write it down in the Book of Grudges and resolve to take bloody vengeance when they can. While doing so, the people they're attacking defend themselves, killing at least one dwarf. Well, that dwarf also has to be avenged. The dwarfish language has no word for 'forgiveness'.
There's some of this also in Hamlet. In the course of avenging his father, Hamlet ends up with Laertes after him for killing his father (which was, ironically enough, an accident). Though Laertes going after Hamlet wasn't simply because Polonius was killed, but rather because Ophelia committed suicide not long after, having gone bat-shit crazy upon hearing of her father's death.
In Romeo and Juliet, the Capulets and the Montagues alternately avenge every death that the opposing family caused. It's been going on for so long that the two warring families have forgotten exactly who started it and over what.
Titus Andronicus is one long and extremely bloody Cycle of Revenge between the title character and Tamora, the Queen of the Goths.
The Jets and Sharks in West Side Story; unsurprisingly, since the musical is modeled on Romeo and Juliet.
The Marriage of Figaro is a bloodless variation of this- characters in an endless cycle of messing with each other's heads in revenge for what they did earlier in the show
Sometimes, the already twisted path of revenge is even more non-linear than normal, thanks to time-space anomalies and reincarnation, as is the case in Soul Nomad & the World Eaters. One might invoke the wrath of another for avenging one's past self, while also unwittingly putting oneself on one's own hit list along the way somehow. That can't be good for the space-time continuum or anyone else involved!
Most of which get subverted to some degree or another, at least in the first Knights of the Old Republic game. Jagi wanted to take revenge on Canderous for allegedly abandoning his men during a battle to seize a tactical advantage. When facing down Jagi, one of the options is to point out that Canderous probably saved a lot more lives by breaking from the battle plan. Jagi commits suicide when he realizes that Canderous's actions were perfectly acceptable under the code of the Mandalorians.
Bastila and her estranged mother, Helena, have a chilly reunion on Tatooine. Helena then requests that you go out to the desert to retrieve her late father's holocron. When you do retrieve it, Bastila is tempted to keep it just to spite her mother. Turns out that Bastila's father was treasure-hunting to fund the dying Helena's medical treatment.
If you're inclined towards Darkness, you can encourage Mission to abandon her deadbeat brother to the Exchange (organized crime) in revenge for him abandoning her on Taris.
Juhani lampshades this trope when talking about her past, how "Those who had been wronged saw their chance at revenge. The oppressed became the new generation of oppressors" after the Jedi left Taris to fight more battles against the Mandalorians, bitterly lamenting that "the non-humans were never treated well in either case." There's also some cut dialogue for Juhani where she admits that she still hates and fears Mandalorians for committing genocide against her people, and voices her disapproval of Canderous among the crew. In one of the options, you can propose she go and kill him. She is still enough of a Jedi to balk at the idea of cold-blooded murder. However, when you meet up with Xor, a mercenary who participated in the Cathar genocide, and who later murdered Juhani's father in a bar fight and tried to buy her as a slave, those with darker tendencies can cheerfully encourage her to skewer the jerk on her lightsaber.
And when it comes to subverting this trope, Carth's the master. His primary motive for 3/4 of the game is to get revenge on his former mentor (and to a lesser extent, all Sith) for destroying his homeworld, killing his wife, and training his teenage son as a Dark Jedi. When he finally kills Saul, Saul uses his last breath to take revenge on Carth by announcing his friend (if you play male) or lover (if you play female) is none other than Darth Revan! After the last Star Map is found, Carth admits that revenge didn't give him any peace, and that he can no longer hate you, despite what you have done as Revan. With a female Player Character, he elaborates further, saying that his promise to protect you has given him a new reason to live.
To some degree, the motivations of most of the principal players of the Metal Gear Solid series are wrapped up in revenge upon revenge.
Throughout the early parts of Tales of Symphonia, Lloyd gets pissed off at the way Desians treat humans. Kratos implies (in typical Tales fashion) that there's an underlying reason. There is: once they get to Tethe'alla, they learn that the half-elves there are victims of particularly cruel discrimination.
In the John Woo game Stranglehold, Tequila gets pissed at Wong for turning his partner against him, having Billie killed, and then kidnapping Teko, leading to the Cowboy Cop seeking vengeance upon him. Wong in turn hates Tequila's guts, which is why he didn't want him and Billie together to begin with, and he wants revenge himself on Tequila for killing his son Johnny Wong from Hard Boiled, who was behind the attack that killed his partner in the beginning of the movie and was very much an utter psycho deserving of death.
In the Touhou game, Imperishable Night, Kaguya Houraisan and Fujiwara no Mokou respectively want to kill each other as revenge for the numerous previous successful attempts on each other's lives — they're immortal, and can regenerate even if their bodies are entirely destroyed. And it all started when Kaguya rejected Mokou's father's marriage proposal, 1300 years ago. This is just one of Touhou's many moments.
The reason behind the Alliance and the Horde being more or less openly at war in World of Warcraft after being allies at the end of Warcraft III. Some people just couldn't get over the fact that the enemy they had fought for so long wasn't an enemy anymore.
On PvP servers, you can easily experience a Cycle of Revenge first-hand.
A similar issue exists between two Outland factions, the Aldor and the Scryer. While they both are part of the same alliance, players are forced to choose between the two.
Camp Taurajo in the Southern Barrens becomes the start of one. The Alliance sacks Taurajo, the Horde responds by killing the General who carried out the attack, and the other Alliance leaders swear vengeance on the Horde for the assassination. Ironically, General Hawthorne was trying to avoid civilian casualties because he didn't want a Cycle of Revenge, but didn't factor in the quillboar who were mortal enemies of the Tauren.
It's also hinted he didn't count on the rabidly anti-Horde ambassador. The Ambassador's interest in the Horde's desire for revenge, the easily located spy with an itinerary for the General's journey, and the speed with which a replacement is found are too convenient. This Cycle was planned.
Taran Zhu of the pandaren calls both sides out on this in the latest patch:
Taran Zhu: ENOUGH!! There will be no more bloodshed today. I see now why your Alliance and Horde cannot stop fighting. Every reprisal is itself an act of aggression, and every act of aggression triggers immediate reprisal. [...] SILENCE! YOU must break the cycle. It ends TODAY. Here. The cycle ends when you, Regent Lord, and you, Lady Proudmoore, turn from one another. And walk. Away.
However, as many players have noted, Taran Zhu's view of the situation is hopelessly ignorant. Had this taken place in early WoW, it would have made sense, but as of Mists of Pandaria, the conflict between the Alliance and Horde has become a war of aggression on the Horde's part; as of his speech, the Alliance is fighting only to survive against Garrosh's increased aggressiveness and to stop his attempts at conquest, not out of some petty grudge against the Horde. Considering Zhu himself had literally just finished killing a group of Zandalari and Mogu before making that speech, many players consider him a massive Hypocrite.
Not to mention that the whole "breaking the cycle" bit has already been attempted and failed. After Garrosh nuked Theramore, Jaina was poised to level Orgrimmar with a tidal wave in retaliation, but was ultimately talked down and didn't go through with it(And, in fact, ended up going the exact opposite way, using her newly gained position as head of the Kirin Tor to make Dalaran into an example of a place where Alliance and Horde can work together peacefully! It just took the Horde stabbing her in the back for about the twentieth time for her to go back on that.). Yet Garrosh has continued the war anyway. Yeah, a funny thing happens when you arrogantly interject your opinions about something you've willfully avoided actually learning anything about - you tend to be wrong.
And Taran Zhu isn't so innocent himself, He and the Shado-Pan's immediate reaction to the awakening of Lei Shen, a mogu leader whose main objective was to create order in the chaos following the titans leaving Azeroth, is to immediately attack, on the grounds of "They did something to us in the past". Notably, the Mogu kept prisoners, the Horde did not.
Subverted in Kung Lao's ending of Mortal Kombat Gold; he attacks the Shokan Goro during a peace treaty signing as a ceremonial strike of revenge for Goro's brutal murder of his ancestor in an earlier MK tournament. Goro naturally believes that Lao is wanting to continue the fight for vengeance, but Lao tells him no, the attack was just to let the big lug know he hasn't forgotten what he did all those centuries ago, but is willing to put aside their differences for the sake of peace. Goro agrees, hinting that were his and Lao's ancestor's fates were reversed, Goro's own son would've likely been the one asking Lao (or his ancestor, since being Champion of MK gives you natural immortality) for peace.
The Killzone series sets this up. The feud between Helghan and the ISA goes back for generations, with the actions of the series being the Second Intersolar War.
Subverted in Tales of Legendia. Near the end of Chloe's character quest in her confrontation with Stingle, the man who killed her parents to get money for his sick daughter, she is all but willing to kill him... until his daughter, whom she had grown close to at that point, picks up her father's sword, swearing to protect her father and take revenge upon Chloe if she kills, helping to snap Chloe out of her growing Knight Templar attitude.
The Nature of the Beast Quest in Dragon Age: Origins revolves around a vicious Cycle of Revenge. Long ago, a group of humans attacked the Dalish Elves in the Brecilian Forest, killing the son and raping the daughter (who was later Driven to Suicide) of the elven Keeper Zathrien. In his rage and grief, Zathrien summoned a forest spirit and bound it in the body of a wolf using his own blood, creating Witherfang. Witherfang then cursed the humans, and turned them into the first werewolves. Centuries later, those humans' descendants are still cursed. Under the guidance of Witherfang (who has recently gained sentience and intelligence as the Lady of the Forest), this new generation of werewolves are attacking the Dalish and spreading the curse to them, partly for revenge against Zathrien (who is still alive because he is bound to Witherfang) and partly because they are trying to force Zathrien to undo his curse. The werewolves believe they are being unfairly punished for their ancestors' crimes. Zauthrien believes that their current actions prove that they are just as savage as their ancestors and deserve the curse no less. Ultimately, it's up to you to decide how this cycle is resolved.
Even if you cure the werewolves and end the curse, the cycle threatens to perpetuate itself with Dalish elves who now want revenge on the former werewolves for killing members of their clan. Hawke can encounter the daughter of a Dalish hunter-turned werewolf in Dragon Age II who is threatening to murder one of these former werewolves. Hawke can choose to peacefully resolve the situation, leave the former werewolf to his fate or kill the elf and her companions.
This Trope also comes to play if you're a Human Noble. The Warden avenges his/her parents' murders by killing Arl Howe during the last 1/4 of the game. Later, in the Awakening expansion pack, one of your first party member candidates is his son Nathaniel, who was about to assasinate the Warden as a revenge for his father's death, but got captured for trespassing before he had the chance to slip a dagger between his target's ribs. Part of Nathaniel's Character Development later on is cutting the cycle once he learns and understands what a bastard his father was and that he had it coming.
No More Heroes: the final boss in the first game says as much without going into all the symbolism, but the second game does this even more. The first boss is Helter Skelter's younger brother who wants revenge. Matt Helms killed his parents as a ghost for leaving him in a burning house to die. Two assassins come back to fight you despite dying in the previous game. And the final boss, Jasper Batt Jr. has Bishop murdered at the start of the game out of revenge for Travis killing his father and two brothers in the side missions in the last game, something the player probably doesn't even remember.
Invoked in the Burnout series, namely Revenge onward. It keeps track of everybody you've started a rivalry with, and rewards you for getting revenge or keeping your rival from doing so.
Saints Row 2, as mentioned in other Revenge tropes, particularly the Brotherhood arc. An interesting aversion by Johnny Gat, the most psychotic killer in both games; even though his Love Interest was slain, killing all the Ronin was no more or less the same business it was before, just a little more personal. The other revenges through the remaining arc hardly seem connected to each other.
The single-player campaign of Tribes: Vengeance, true to its subtitle, is driven almost entirely by someone's desire for revenge and the protagonists are rotated all the time.
The entire point of Cactus's short "art game" Space Fuck!. Two neighboring planets in space; every thirty years, on one of the planets, a warrior comes out of the tunnels where he lived his entire life, and finds ruins of a thriving city on the surface. A survivor tells him that a man from the other planet massacred everyone. The warrior decides to get revenge, hops into a ship that happens to be nearby and flies to the other planet to massacre the inhabitants there. Then he descends into that planet's tunnels, meets a woman and has a son with her. Thirty years later, the son comes out of the tunnels and finds ruins of a thriving city on the surface, and learns that a warrior from the other planet is responsible. He decides to get revenge on the other planet, flies over there and kills everyone, then descends into the tunnels where he meets a woman... After a couple iterations, the game outright announces: "Vicious Cycle".
Lara Croft and Werner Von Croy use the trope on each other throughout Tomb Raider: The Last Revelation and the final chapter in Tomb Raider Chronicles. Teenage Lara goes on an expedition with Von Croy and is forced to leave him behind when his tampering with the Iris artifact causes the area to collapse and traps him. Von Croy is rescued some time later and keeps the artifact while being bitter towards Lara who he thinks abandoned him. Lara then infiltrates Von Croy's research building and steals the Iris artifact from him. This in turn causes Von Croy several years later to seek revenge by hiring mercenaries to stop or kill Lara in Egypt so that he can claim the Amulet of Set (succeeding) and then he goes on to capture Lara's friend, holding him hostage in exchange for the Armor of Horus. After Lara's apparent demise when the pyarmid she is in collapses as Von Croy watches in horror, Lara escapes some time later in The Angel of Darkness and is angry at Von Croy for leaving her back in Eygpt. The entire cycle of revenge is finally broken when a third party unrelated to the two characters kills Von Croy.
A variation is the key story trope of Infinity Blade. The game starts off with the tyrannical God King killing one who opposes him. Then, some 20 years later, that man's son comes to avenge him — and after fighting through the God King's castle, also gets killed. And so on, and so on, until you either manage to kill the God King, or fight him to a standstill and agree to join him. In the former case you've accomplished nothing except making some powerful new enemies who have no reason to hold the man who killed the God King in any higher regard than they held the God King. Then, you skip to the next in the bloodline avenging his father, because the game is built around this preconception. In the latter case you find out the God King was one of the good guys — unlike the other Deathless, he doesn't think that being immortal gives him license to be a colossal jerk for no reason, and the whole exercise was The Plan to lure powerful warriors to his castle, where he'd either kill them to enhance his power or recruit them as his champion so he could take on the others. If that isn't pointless enough, the sequel reveals that your character wasn't actually avenging anyone in the first place. He's an amnesiac immortal, with each reincarnation believing his previous incarnation to be his dead father in need of avenging.
In chronological order: Vriska cripples Tavros, Aradia sends ghosts to torment her, Vriska mind-controls Aradia's boyfriend into killing her, Terezi informs Doc Scratch about one of his items currently owned by Vriska - which he then explodes, blowing off Vriska's special eye and an arm; Vriska then pulls out a three-step mind-control reacharound to make Terezi stare into the sun and go blind. It all happens in an immediate succession. Some time later, after Tavros, with whom everything started, has apparently forgiven her, Aradia (now as a ghost inhabiting a robot) delivers a near-fatal beatdown to Vriska. After Vriska awakes as her dream-self, Terezi merely slaps her, ending the cycle.
Some time later, Tavros decides that Vriska must be stopped (after more Kick the Dog moments from her) and attacks her, getting irrevocably killed in retaliation. Terezi finds his body and immediately deduces who did it, starting the cycle anew.
The cycle is finally broken when Terezi kills Vriska to stop her from following a course of action that would doom the other Trolls.
It is then revealed that the cycle began earlier than that. As in, during their ancestors' time.
The plot of Juathuur is for the most part about this. Thomil is the only one concerned with actually breaking the cycle.
In The Order of the Stick, the conflict between the Sapphire Guard (an order of Lawful GoodPaladins) and the allegedlyAlways Chaotic Evil goblin races is a perfect example of this. The story makes it abundantly clear that both sides are at fault, but that the destruction of Azure City at the hands of Redcloak's hobgoblin horde is a direct consequence of the Azurites' arrogance in engaging in a preemptive genocidal crusade. For his part, Redcloak is only too happy to continue the cycle of atrocities.
Vaarsuvius also gets some quality time with this trope in the arc with the vengeful black dragon and goes to some rather extreme steps to end it. Unfortunately, this comes at the price of owing his/her soul to some fiends who don't plan to wait for his/her death to collect, and s/he still gets hunted by agents of Tiamat, the goddess of vengeance and chromatic dragons, who is less than pleased about a full quarter of the black dragon population getting wiped out of existence thanks to V.
Oh, and those "extreme steps"? They killed off a plot-relevant family of NPC guardians, leaving one of the Gates defenseless.
Happens in the The Blackrock Chronicles. First Sjin attempts to steal from Duncan, who attacks Sjin in retaliation, leading to a massive Tekkit Server war that destroyed pretty much everyone's game. The plot of Rythian's series then involves him heading out to get revenge against both Duncan and Sjin. Duncan, fearing Rythian's warmongering, traps him in a forcefield and builds a nuke under his castle, while Sjin kidnaps their Dinosaur and it all just escalates from there...
The fake feud between The Nostalgia Critic and The Angry Video Game Nerd was like this at first as both countered perceived slights, before turning into a general hatred that culminated in a decisive final battle. Twice, actually. It's all a joke, so that much is deliberate.
The feud has been settled and started up again twice as well, finally being settled for good (for now at least) in To Boldly Flee.
In the Global Guardians PBEM Universe, Ultra-Man and Baron Malthus have been battling each other since World War II. It stopped being about "preventing injustice" (for Ultra-Man) or "committing a crime" (for Baron Malthus) a long, long time ago... no, these days it's strictly personal.
In the second Jobe story of the Whateley Universe, Jobe and Counterpoint get into a cycle of revenge at Superhero School Whateley Academy. Jobe wins a sparring match in aikido class, but he does it with poisons (Jobe starts the story with human strength and speed, just talent as a bio-devisor, while Counterpoint has strength, speed, a telekinetic shield, and any other powers he wants to copy). Counterpoint can't let it go, since he's some sort of incarnation of Ares. He gets some muscle to help him pound Jobe. Jobe can't let it go, since he's the crown prince of Karedonia (his father is a supervillain) and has obligations to make sure people know he can't be pushed around. At the end of the story, they are both in the hospital, and at least one of them might be hospitalized for a long time. And they haven't given up their grudges.
Gargoyles grabs hold of this theme firmly from multiple angles. Goliath wants revenge against the Vikings for his clan's genocide, Macbeth wanted revenge against Demona for her treachery, Demona wanted revenge against all humans... the list continues on, right down to a nameless guy who is always being shafted by the Gargoyle exploits, who was able to break his own cycle by settling for shooting a Gargoyle in the face with a Pie Cannon.
By the end of second season, Macbeth and Goliath manage to drop their respective beefs, but Demona never lets go of her vendetta against humanity (Word of God has stated she eventually will, thanks to her daughter), and she in turn is pursued by a family of Hunters sworn to kill her.
Two of the three most recent Hunters drop the axe thanks to Elisa's influence and the realization of how much their blood feud has cost them (up to and including one of them ending up paraplegic), but the nicest of the three snaps, and the cycle is perpetuated. Interestingly, the leader of the three most recent hunters admits it has been long forgotten why they hunt Gargoyles. All they know is that it is their family legacy.
There was pretty much a Seesaw of Revenge going on in the backstory, starting in 997 and possibly ending in 1058: In 997, Gillecomgain's father, Mail Brigti, was killed in battle against Findlaech, and although Findlaech didn't strike the killing blow (and didn't even want to kill Mail Brigti anyway), Gillecomgain still blamed Findlaech for Mail Brigti's death. Then, in 1020, partly to avenge Mail Brigti and partly because Duncan commanded it, Gillecomgain murdered Findlaech. In 1032, Findlaech's son Macbeth learned that Gillecomgain had killed his father and killed Gillecomgain for revenge; then, in 1040, he learned that Duncan had demanded his father's death and killed Duncan as well. In 1057, Duncan's son Canmore "killed" Macbeth to avenge Duncan, and Macbeth's son Luach swore vengeance against Canmore. Whether the cycle was broken when Luach died in battle against Canmore in 1058 is debatable.
Gargoyles does contain one aversion to this trope. Xanatos refuses to pursue revenge on any of his enemies, calling it "a sucker's game". Judging by what happened to the other revenge seekers on this show, Xanatos may be right. Xanatos did pursue revenge, albeit reluctantly, in "Double Jeopardy," but he was also thoroughly defeated by Thailog in that episode.
This exchange highlights it beautifully.
The Sisters: You must give them the code. Demona: (In a trance) I will have vengeance for the betrayal of my Clan... Vengeance for my pain. The Sisters: But who betrayed your Clan? And who caused this pain? Demona: (Getting agitated) The Vikings destroyed my Clan! The Sisters: Who betrayed the castle to the Vikings? (Note: It was Demona.) Demona: The Hunter hunted us down. The Sisters: Who created the Hunter? (Note: Demona did) Demona: Canmore destroyed the last of us... The Sisters: Who betrayed Macbeth to Canmore? (Note: Demona) (Pan to wide-eyed 'What have I done' look on Demona's face) Goliath: Your thirst for vengeance has only created more sorrow. End the cycle, Demona... give us the code... Demona: (Tears forming while saying slowly) The access code is...alone.
In The Real Adventures of Jonny Quest, the Quest kids find themselves caught in a hidden war between the descendants of Revolutionary War loyalists and the Continental Army agents sent to kill them. The original point of the fighting (recovering the original Declaration of Independence, which the Loyalists stole) is all but forgotten (not to mention 200 years moot), and is primarily boiling down to killing the guy on the other side for killing your father, or him coming after you for killing his (usually both).
In The Legend of Korra has one in Yakone's family. Yakone was a vicious mob boss who was an extremely powerful bloodbender, forcing Aang to take away his bending. Yakone raised his children as Tykebombs to take revenge on Republic City and the Avatar for this. This abuse caused one of his sons, Noatak, to seek revenge on Benders in general, becoming Amon, while his brother Tarrlok ended up becoming a pseudo-fascist politician with ambitions of ruling Republic City. Ultimately, both brothers ended up becoming Yakone's instruments of revenge, in spite of their attempts to escape his plans. Tarrlok finally ends the cycle by killing himself along with Amon, ending Yakone's legacy along with them.
Thundercats 2011 has this as an undercurrent of the generations-long war between the Cats and the Lizards. Implicitly, this is Lizard General Slithe's motive over a long career of fighting the Cats.
Ultimately subverted before it could truly begin in the My Little Pony: Friendship Is Magic episode "One Bad Apple." In it, Apple Bloom's visiting cousin, Babs Seed, joins local mean girls Diamond Tiara & Silver Spoon in bullying the Cutie Mark Crusaders to the point that they employ a Batman Gambit prank to get her back. However, when told near episode's end that Babs herself had been a victim of bullying due to her lack of Cutie Mark the Crusaders realize part of what drove her actions and try to stop what they've begun so as not to become bullies themselves.
As already mentioned, a widely common phenomenon in cultures all over the world before the emergence of public prosecution, public executive (in other words, police), prison sentences (and, well, public prisons), and the state's monopoly of violence in general. Before these things became institutions, people all over the world were used to take justice and the enforcement of laws and sentences into their own hands.
This is possibly the natural state of affairs when there is no organized society. All conflicts are resolved with physical violence and revenge is the sacred duty for the wronged lest the wronged lose his honor. This happens also everywhere where central government is weak, remote or effete.Once such culture of honor and vendetta has been born, it is almost impossible to weed out anymore.
To prevent cycles of revenge from going on forever, or turning into spirals of revenge, the Anglo-Saxons, as well as many other medieval societies had the institution of "wer-gild", or blood money. Someone outside the feud would come in and decide who had suffered the most (i.e., which side had suffered the most murders). The side that had suffered less would then have to pay a fine to the others' side proportional to the overzealousness of their revenge killings.
There are several tribes particularly in South America and Africa that are plagued by this, having been stuck in perpetual warfare for generations because each death must be avenged with death.
The culture of Vendetta on the islands of Sicily and Corsica caused this kind of thing to happen until very recently (and maybe it's not quite all over yet).
On Corsica, this combined with the separatist movement and the tendency of both feuding families and separatists to use bombs as weapons of choice has led to the stereotypical association of the island in French media (including comics) with the onomatopoeia boum.
This cycle of vendetta has led in many regions to severe depopulation as all males have either been killed or forced to flee due to centuries of vendette. In Albania it is commonplace in such situation for a woman to take the gender role of a male (to have "social sex change").
A lot of gang violence boils down to this. Most being retaliations for other gang hits.
World War One. The Christmas Truce of 1914, as well as the general 'live and let live' attitude of 1914-15 (in which there were unofficial ceasefires wherein both sides tacitly agreed not to shoot each other), were unthinkable by the end of 1916. Too much blood had been spilt, everyone had lost too many friends, and the General Staffs on both sides had tried to encourage agression by frequent patrols/'trench raids'. The result was a sort of savage joy in the opportunity to kill the enemy in defensive engagements (in which they would be vulnerable to machine-gun fire) and to 'get at them' (in hand-to-hand fighting, preferably) when on on patrols/raids or on the attack. The Cycle of Revenge is the main reason that the armies engaged on the Western Front (French, British, German, Italian, Austro-Hungarian) didn't simply fall apart from low morale, despite numerous rebellions by French troops and the enormous underlying resentment for what was basically a pointless war.
The Hatfield-McCoy feud, which, according to popular lore, began with a dispute over a hog and eventually led to the murder of dozens of people. (The real reason for the feud probably had more to do with jealousy and a dispute over property rights in the valley where both families lived.)
Most wars between Maori tribes were "revenge wars", where they would try and get "utu" for their fallen chief, by killing the other tribes chief.
In Northern Ireland during The Troubles, cycles of revenge killings known as "tit for tat killings" were very common. Where random protestants or catholics were killed within hours of another killing-which would lead to another random killing.....
Germany & France between 1870 and 1945. Germany's resounding victory in the Franco-Prussian war and subsequent annexation of territory led to 40+ years of "Revanchism" (from the French revanche, meaning "revenge") being a dominant political movement in France and to France seeking alliances and preparing for another war with Germany. And then the ethnically-German Habsburgs' Generals use the excuse of Archduke Franz Ferdinand's assassination to annex Serbia, which indirectly (once Russia committed itself to supporting Serbian independence) gave France an excuse to participate in World War I once Germany had demanded they give up several strategic fortresses (upon threat of war). A decade-and-a-half after the French & Allied victory in World War I, the Nazis came to power and (eventually, once war broke out over Poland) pursued their own agenda of revenge against France. Luckily after World War II, in which both nations were devastated and left reliant on US support in the face of possible Soviet aggression, they decided to work together...
It went back further than that. From a German point of view, 1870/71 was payback for the humiliating defeats of the Napoleonic Wars (yes, they had beaten Napoleon in the end, but not without help from other great powers, most notably Russia and Great Britain). While in France, the victory of Jena and Auerstedt in 1806 was seen as revenge for the humiliating defeat at Rossbach against the Prussian army in 1757 during the Seven Years' War, which in turn was seen by Germans as revenge for Louis XIV's wars of aggression, and so on until the middle ages. People in all seriousness talked of the "hereditary enmity" (Erbfeindschaft) between Germany and France, but that term actually first was coined to describe the long-running enmity between the houses of Habsburg (Austrian Archdukes, Dukes of Burgundy, Kings of Naples and Sicily, Holy Roman Emperors, and sometime-Kings of Castile and Aragon [Spain]) and Valois/Bourbon (Kings of France) that went back to Francis I of France and the accession of Charles V Holy Roman Emperor in 1519.
The Norsemen during the Viking age were infamous for this. If a man felt wronged by another, meaning an insult or an act of violence, there were four ways to resolve the conflict.
They could reach a settlement, tallying damages for both parties and having one pay a restitution to the other. Any man was honour-bound against breaking such a settlement.
Next there was the option of taking revenge. If a family member had been killed, his relatives as far related as cousins (including in-laws) were obligated to avenge the victim. With communities being small, it wasn't that uncommon for men to have to choose families as they had relatives in both, and usually, it ended up with entire communities fighting for generations. A man was honour-bound to avenge an unsettled vendetta, and the only alternative if he was unable or unwilling was fleeing the country.
If a Viking wanted revenge without starting a blood feud, they would sometimes make their case at a thing (a court of chiefs and nobles). And while revenge killings were considered good and just, legal action was seen as underhanded and hostile, and as such was reserved for only the most serious of circumstances. Sentences were fines, banishment, or being declared outlaw (effectively a dishonourable, unavengable death sentence for you or anyone who helps you).
Lastly there was the option of demanding a Trial by Combat. This meant either death, or a verdict of banishment or outlaw, for the loser, with a risk of death from wounds for the victor too.
Blood revenge continued in the Norse-lands even as they became monarchies, with the chieftains as nobles and jarls, until the 1200s, when the practice was banned in Norway and Sweden and replaced with courts and laws.
The Montenegrins in particular are especially infamous for this. It even has its own name: Krvna Osveta, Blood Feud. Though it isn't as common nowadays, it still does happen in more remote areas.
The Balkans in general. The breakdown in Yugoslavia involved (at least per the excuses given): Serbians taking revenge on Croats for siding with the Germans in World War 2 in revenge for the Serbians doing something to the Croats even earlier, and everyone against the Muslims due to the Turkish invasions of the 1500s, and so on and so forth. And then there are the Greeks and the Turks...for everyone else in the area, the joke goes that they're starting to get over grudges dating back to the Roman Empire. The Greeks and the Turks involve a revenge cycle going back to Classical Greece and the Persian Empire.
Many Islamic Extremists use revenge for The Crusades to justify their hatred of Christians. Their terrorist attacks in turn lead to hate crimes by Extremist Christians and other groups against followers of Islam in general, leading to more violence from the Islamic Extremists in a never ending cycle.
Sadly, this is Truth in Television and a common Freudian Excuse for Real Life school bullying and cyberbullying cases. Some victims of school bullies eventually snap and go on a school shooting. Victims of cyberbullying who commit suicide will eventually lead to their friends or families hunting for the cyberbully's blood.
In intelligence circles, this is known as "blowback."
In the War of 1812, the British would commit war crimes on American settlements in response to "American savagery" inflicted on British-American settlements, which in turn would cause the Americans to burn more British settlements, in revenge for "British savagery". The most triumphant example of this was when the Americans burned the Canadian city of York (modern Toronto, the largest city, and the De facto capital of British Canada at the time) only for the British to respond by torching the public buildings of Washington DC. In the same war, soldiers from both sides would routinely collect the scalps from the corpses of enemy soldiers as trophies. Newspapers on both sides demonised the other side for this practice, calling their enemies "little more than Indian savages", but at the same time, newspapers would be willing to turn a blind eye to this exact same activity on their own side. Since the war ended with the exact same borders that existed before the war, neither side gained anything from this activity except a bunch of burned down ruins where wealthy and thriving cities used to be, a large number of dead or displaced civilians, and a massive reconstruction bill costing thousands of pounds for both sides. But hey, at least they got a nice scalp collection out of it!