One Piece leans into the idea of revenge more than most anime, especially as a shonen. Over the series' two-decade runtime, there have been many instances where one character attempts to right a wrong dealt to them by another.
What makes the series particularly interesting is that heroes enact just as much payback as their antagonistic counterparts. Usually, their actions are justified through years if not decades of previous injustice, with context making the impending beat-down even more cathartic. Such instances prove that revenge is not an inherently villainous concept.
10 Luffy Avenged Nami When Fighting Arlong
Ever since Orange Town, Luffy quickly appreciated Nami as one of the Straw Hats' founding members. When she attempted to betray him for Arlong's sake, he visited their island and uncovered the truth.
The villainous fish-man had been hoarding her people's resources under threat of violence. By defeating Arlong, Luffy liberated Nami's home, earned her trust, and ensured that his fractured band of pirates would never trouble an innocent soul again. Arlong's crew scattered after his defeat, having finally realized how weak he was compared to even a novice fighter.
9 Luffy Punched Charloss To Stop Him From Buying Camie
Charloss was unpleasant even for a Celestial Dragon. He treated other people like property, using the threat of the Marines' power in order to exert his dominance. When the villain attempted to purchase Camie during the Sabaody Black Market Auction, Luffy could no longer stand him.
Rather than watching his friend get enslaved, Luffy knocked Charloss out in one punch. Although this was an incredibly satisfying revenge moment, it had dire implications since it drew Kizaru's attention to the region. At the time, not even the entire Worst Generation could deal with him.
8 Usopp Defeated Jango Of The Black Cat Pirates
The Black Cat Pirates threatened Syrup Village, attempted to steal Kaya's fortune, and nearly assassinated Luffy. To make matters worse, its second in command, Jango, attacked a trio of kids that identified as Usopp's crew.
Despite Usopp's cowardice, this finally prompted him to spring into action. After Zoro carved him a clean shot, he unleashed a barrage of projectiles against Jango that took him out of the fight. It was Usopp's way of avenging himself and illustrating that he had the potential to become a great warrior of the sea.
7 The Samurai Attacked Kanjuro After Uncovering His Identity
Even after it became abundantly clear that there was a traitor among the samurai, none wanted to accuse their comrades. It made Kanjuro's reveal especially painful, as Kin'emon considered him a brother up until that time.
Regardless, the heroes had no qualms about fighting him after his treachery came to light. Kikyo fully intended to kill him during their first clash outside Onigashima, and Ashura Doji gave his life to minimize the damage the spy inflicted. Kanjuro's unapologetic evil made the revenge enacted against him more satisfying.
6 Luffy Stopped Eneru From Abducting Nami
By the time Luffy caught up with Eneru on Skypiea, the villain had much to answer for. So far, he'd electrocuted Sanji, Zoro, and Usopp to the brink of death, abducting Nami in hopes of procuring her allegiance. To make matters worse, Eneru also intended to massacre his own people since he got bored with them.
As a result, Luffy's attack was extremely personal and partially driven by revenge. He was the only person who could have opposed Eneru, as the villain's Logia body made it difficult for most to hit without using Haki.
5 Trafalgar Law's Fight Against Doflamingo Was A Long Time Coming
Trafalgar Law harbored a grudge against Doflamingo ever since Corazon's death. He was more invested in the warlord's undoing than Kaido's, having attempted to defeat him once before during the arc.
Although Law ultimately may not have been Doflamingo's downfall, he weakened him considerably by injuring his internal organs. He was also instrumental against Trebol, who would have been a significant obstruction to the heroes' efforts if not dealt with promptly. Having sought revenge for almost a decade, Law's justice was incredibly satisfying.
4 Cat Viper & Dogstorm Avenged Zunisha Against Jack
The grudge between Jack and the Minks was personal. During the Zou arc, Jack laid waste to their civilization, decimated their people, poisoned the land, and even attacked Zunisha himself. Were it not for Momonosuke's presence, he could have even destroyed the entire Mink race.
When Cat Viper and Dogstorm encountered him at Onigashima, their vengeance was swift and merciless. Both heroes brought the mammoth to his knees in a matter of moments, empowered by the full moon. Jack lost so completely that he felt obligated to apologize to Kaido.
3 Nico Robin Avenged Sanji Against Black Maria
Black Maria was one of the most sinister Tobi Roppo. She quickly identified Sanji's chivalrous code and used it to relentlessly beat him. Even though Sanji was much stronger than she was, the woman's size and arsenal of abilities proved threats by themselves.
Maria insisted that Sanji summon Nico Robin so that she could capture her for the Beast Pirates. When Sanji finally did, Robin was furious about how Maria had abused her teammate. This prompted a brutal fight where Robin illustrated the full scope of her abilities for the first time since Skypiea.
2 Sanji Avenged Nami Against Absalom
Despite Absalom's invisibility and bazooka, Sanji wasn't intimidated. After discovering how he abducted and attempted to marry Nami, the young hero bludgeoned him without remorse. It illustrated the darker side of Sanji's chivalry and that he wouldn't abide trespasses against women lightly.
However, Sanji also had a more ridiculous grudge against Absalom. He was upset that the villain stole the Clear-Clear fruit since he wanted it for himself. Predictably, he had less than noble intentions for the ability to turn invisible.
1 Nico Robin Snapped Spandam's Spine At The End Of Enies Lobby
When the Straw Hats attempted to escape Enies Lobby, Spandam gave chase. He did not want to let the pirates who destroyed a significant Marine bastion get off easily, especially since he would have nothing to show for the carnage.
However, Spandam failed to remember that a vengeful Nico Robin was onboard the Going Merry. She used her Devil Fruit in order to viciously snap the man's spine in two, taking him out of commission and administering long overdue revenge for her capture. Unfortunately, Spandam's injuries were not permanent since he reappeared later alongside Lucci.