Technology is becoming an increasingly important aspect of the One Piece universe. With the Egghead arc in full swing, fans are beginning to understand the full extent of how far a strong scientist can go, as seen through the recent introduction of the Seraphim.
However, only a few characters can make the claim of fighting and devoting themselves almost entirely to technology. By identifying them and their roles in the story, it becomes easier to gauge if science may be a rival to Devil Fruits and Haki as the series enters its final and most intense chapters.
10 Doctor Vegapunk Is A World Class Scientist
Doctor Vegapunk is a world-class scientist and the creator of the Pacifistas. Although once in service to the World Government, they have recently turned on him and ordered for his downfall. So far, the Straw Hats have met a young woman who may represent one of Vegapunk's avatars.
Still, the doctor's true physical form has yet to be seen, likely remaining one of the Egghead arc's most dramatic reveals for when the time is right. Nonetheless, Vegapunk's connection to many other characters makes him special.
9 Don Krieg Used Technology To Crush His Enemies
Don Krieg may not have been the most powerful antagonist, but he was extremely resourceful. During his bid to claim to Baratie, he used an exploding spear, steel net, and even poison gas against Luffy. He became notorious across the high seas for his underhanded tactics, earning quite the reputation on the Grand Line before Mihawk ruined his career.
Krieg's lack of Haki or a Devil make him the exception. The villain is an embodiment of how far an ordinary man can go with the right tools for the job and enough grit to see it through.
8 Tom Was Roger's Personal Shipwright
Tom was Gol D. Roger's personal shipwright and Franky's adoptive father. After being arrested by the World Government for conspiracy, he helped design Water Seven's sea train, which connected directly to Enies Lobby.
Considering that Tom was responsible for drafting Pluton – the blueprints for a battleship capable of immense destruction – it comes as little surprise that Spandam sought to commission his services. However, he predictably had no intention of honoring his word and arrested him again shortly after he was finished. Tom's fate is currently unknown, but he's likely dead.
7 Sentomaru Was Vegapunk's Personal Bodyguard
Sentomaru was an extremely powerful member of the World Government. Having once served as Doctor Vegapunk's personal bodyguard, he commanded the Pacifstas during the Marineford attack and amidst his quest to destroy the Straw Hats personally. He was moderately successful toward this end, as none were on his level.
While Sentomaru mostly relies on his mechanical servants, he isn't helpless on his own. During his first encounter with Luffy, he used advanced armament Haki to inflict devastating force against him. Luffy used his power as a reference for his own training when learning under Boss Hyogoro at Udon's slave pits.
6 Reiju Is Sanji's Sister & A Member Of Germa 66
Reiju is Sanji's sister and one of Germa's strongest soldiers. Her "Poison Pink" uniform allowed her to fight against some of Big Mom's toughest generals and procure her family's escape from the treacherous kingdom.
Like Krieg, Reiju's unique access to poisons gives her a significant advantage against unsuspecting opponents. It allows her to compliment her brothers' more physical attacks well, ensuring that Germa remains the most powerful empire ever to terrorize the North Blue.
5 Kuma Was More Machine Than Man
Kuma was a member of the Revolutionary Army who joined the Warlord program to closer observe the World Government. Cybernetically enhanced, his human body was gradually replaced until it was difficult to tell how much of the man was left in his mechanical shell.
Regardless of his cybernetic condition, Kuma has shown his humanity by sparing the Straw Hats at Thriller Bark and directly saving them in Sabaody. The World Government noticed and would not soon forgive him. They further mechanized Kuma's body and made him the personal mount for Celestial Dragons.
4 Queen Was Kaido's Top Scientist
Queen was Kaido's third-in-command and an incredibly powerful scientist. His forte was bioweapons, which warranted his title as "the Plague." This was much to the samurai's chagrin, especially when he began infecting a mass crowd of people with his latest blight, the ice oni serum.
Additionally, Queen proved surprisingly competent with mechanical augmentations. He transformed his body so that it could disjoint itself and fire laser cannons from his mouth. When combined with his Devil Fruit, this made him a nearly unstoppable and well rounded fighter that even knocked Big Mom unconscious for a few hours.
3 Caesar Clown Ran The S.M.I.L.E Factory
Caesar Clown was the main antagonist of the Punk Hazard arc and a villain without morals. He worked on projects for both Big Mom and Kaido, perfecting gigantification for the former and enabling the latter's army of Devil Fruit users.
When the Straw Hats threatened to destroy Caesar's factory, he knew he wouldn't be able to stop them all himself. Instead, he unleashed S.M.I.L.E on the island and hoped to petrify them in noxious gas. Were it not for Brownbeard's unexpected aid, he might have even succeeded toward this end.
2 Vinsmoke Judge Was The Tyrant Of The Germa Kingdom
Vinsmoke Judge was a technological genius. His understanding of biological enhancements allowed him to genetically modify his children and create an entire army of loyal soldiers. They proved so formidable that Big Mom coveted his facilities and attacked Germa to seize them.
Judge is also extremely powerful in his own right. He managed to fight evenly with Sanji for several minutes, which is remarkable given the latter's strength ever since the time skip. However, Judge's overconfidence in his knowledge almost resulted in the death of his entire family during the tea party.
1 Franky Is The Straw Hats' Shipwright
Franky is a technological genius. Despite lacking a Devil Fruit or armament Haki, he holds his own through a combination of explosives and mechanical strength. When pushed into a dire situation, Franky may also enter the Iron Pirate, a suit of mechanical armor so durable that not even Big Mom could break it.
Having replaced much of his body with metal parts, the front of Franky's body is nearly indestructible. His back may be a weak spot, though it's still fairly resilient as proven through his victory over Senor Pink during the battle for Dressrosa.