One of the longest-running anime and manga series of all time, One Piece's hold on the anime community is nigh unmatched, and a lot of that has to do with its fight scenes. With its creative animation and unique character designs, the series has carved out its place in the medium's history while also delivering the high-octane action that fans expect from anime.
With so many episodes and arcs, the show has had its share of battles that have changed manga forever. These high-stakes fights happen at least once an arc, showcasing how the One Piece world is constantly evolving and growing more intense for audiences.
Zoro vs. Mihawk
One of the earliest "curb-stomp" fights in the series. It's primarily a test for Zoro as he faces off against the strongest swordsman in the world — Dracule Mihawk, one of the Seven Warlords of the Sea and an extremely deadly pirate. Mihawk had followed Don Kreig's entire crew to the Baratie to eliminate them completely, but Zoro stood in his way as Luffy, Sanji, and the Baratie crew faced off against Kreig.
What follows is a fight that doesn't last longer than a couple of blows, but its effects are widespread and necessary. Zoro's loss to Mihawk gives him the resolve he needs to get stronger, and Mihawk's easy defeat of Zoro puts a power level on the truly strongest pirates of the series — showing that Luffy and his crew still have a long way to go in terms of strength.
Luffy vs. Crocodile (Round 3)
All of Luffy's fights against Crocodile could be contenders for this. Still, his third and last fight is the most impactful for the story at hand, particularly for the nation of Alabasta. After two prior losses to the powerful Logia user, Luffy ends up fighting Crocodile underneath Alabasta in one last desperate attempt to stop him from finding the Pluton.
It is a great fight from an animation and boarding perspective, but it's also the moment Luffy makes himself known to the pirate world on a large scale. Sure, beating Arlong was a huge deal, but defeating Crocodile, one of the Seven Warlords? Now that's going to get the interest of everybody else for sure.
Zoro vs. Mr. 1
A smaller yet equally important fight also happens in Alabasta, with Zoro fighting against the most powerful of Crocodile's enforcers — the deadly Mr. 1, who can turn his body into steel. Before this fight, Zoro had numerous problems trying to cut steel and other metals and viewed it as an internal weakness.
Now, forced with the decision to confront one of his lesser traits, Zoro has to look inward to defeat Mr. 1, and in a glorious moment for the character, he does. It's a powerful scene and one of Zoro's more exciting early victories as he realizes "he can cut anything." This also sets up just how powerful Zoro is to become in the future — particularly after the time skip.
Luffy vs. Bellamy
While it's mostly a gag battle that ends in a single punch, Luffy's first encounter with Bellamy in Jaya has massive ramifications for the story at hand, most of which aren't even known until much later. If anything, this fight is a perfect example of how good Eiichiro Oda's storytelling and foreshadowing is as he meticulously lays out his pieces early.
Bellamy's quick defeat at the hands of Luffy, as we would later find out, would cost him a prominent place in the Donquixote Pirates under Doflamingo, and Bellamy harbored resentment toward Luffy for two years after that incident. It wasn't until the Dressrosa arc that, after traveling to Sky Island, a stronger Bellamy would face off against Luffy again in the name of Donflamingo — only to be defeated again.
Aokiji vs. The Straw Hats
After a brief arc where the Straw Hats have to encounter a pirate named Foxy, they are ambushed by the Marine Admiral Aokiji, a man who can create infinite amounts of ice and has a strange resemblance to Michael Jackson, of all people. He's mostly there for Robin as the World Government views her as a threat precisely due to her abilities.
Aokiji proceeds to curb stomp the entire crew, allowing them to live as he believes Robin's existence alone will leave them dead soon. It is our first showcase of the Marine Admirals and their power. Still, it also sets up Robin's storyline over the next two arcs and gives context for her abandonment and eventual return to the crew throughout Water 7 and Enies Lobby.
Luffy vs. Usopp
Usopp, the lovable liar of the Straw Hat crew, takes a while to come into his own as a character. And nobody feels that way more than Usopp himself, as his inability to help the Straw Hats and feelings of loss over losing the Going Merry force him against his captain.
What follows is one of the most emotional yet necessary fights in the whole series, where Usopp learns to stand up for himself against a foe greater than he is. And while he loses against Luffy and temporarily leaves the crew, it's a critical moment for his character arc, and he begins his path to becoming one of the strongest characters in the series.
The Entirety of the Enies Lobby Arc
This one is probably cheating, but the Enies Lobby Arc is one of the most important sections of the entire series, and it would be remiss to leave out any of the fights from this arc. The whole arc is structured like a rescue movie, with Robin being stuck at Enies Lobby at the hands of CP9 and the World Government, and it's up to the Straw Hats to rescue her.
From Nami getting a massive boost in power from her new Clima-Tact, Chopper's Monster Point revealed, Sanji's Diable Jambe, and more, each of the Straw Hats gets more powerful and showcases abilities that change the game for fights in the future. Now, all of the Straw Hats are forces to be reckoned with, not just Luffy. After that, the series is never the same again.
The Battle of Marineford
One of the most significant events in the One Piece timeline, the war at Marineford, is a turning point for much of the world of One Piece and less of the cast. While Luffy is present for the events, and many of the significant events that transpire here affect him personally, it's on a far grander scale than even him as the Three Great Powers lose much of their balance which causes a shakeup.
Most significantly is the death of Whitebeard at the hands of Blackbeard, who in his dying breath confirms the One Piece's existence. While is death scene is as sad as it is awesome, it's also an important scene for confirming Luffy's goal and belief. By sending the world a message, the world heads into a state of open warfare, which is still going on to this day.
Luffy vs. Doflamingo
Beyond simply being the first time we see Gear 4 on-screen (which remains one of the best power upgrades in the whole series), the fight in Dressrosa against the diabolical Doflamingo is one of One Piece's most significant events. Luffy facing off against the deadly former Warlord is reminiscent of the battle against Crocodile but with one key difference — he isn't doing it for himself this time.
Before the time skip, many of Luffy's fights were done simply because enemies "got in the way." Sure, Luffy cared about the people he saved in the end and wanted what was best for the people, but the fight against Donflamingo was the first time fights against somebody out of selflessness — he knew that freeing the people of Dressrosa was the right thing to do.
The Worst Generation vs. Big Mom and Kaido
The most recent fight and one of One Piece's most visually stunning to date, the Wano County Arc, outside of being the most significant arc of the series since maybe Marineford, has been building to this one moment for episode after episode. Then, in a flurry of fantastic boarding and animation, Luffy, Law, Killer, Kidd, and Zoro, all members of the Worst Generation, head up to fight the team-up of Kaido and Big Mom.
It's a fantastic moment, and the fight is equally as impressive, with glorious animation and Yamato realizing that Luffy is indeed Roger's successor. While it's a fight that is still going on in the manga as of publication, it's sure to be an important event when all is said and done.