The One Piece world is usually fairly straightforward as far as its heroes and villains are concerned. The former are paragons of morality who never need underhanded tactics to save the day, whereas the latter are monstrous brutes who will always be defeated by the end of the arc in one way or another (barring Marineford).
However, there are rare exceptions to this otherwise binary dynamic through the series' compelling antiheroes. They help to morally nuance the situation, finding ruthless solutions to difficult problems and making sure that the Straw Hats always stay on their toes. Such characters are worth acknowledging for their contributions.
10 Smoker Was Honorable For A Marine
Captain Smoker was previously one of Luffy's most dogged enemies. He hunted him across the East Blue, nearly even managing to capture him during a fateful confrontation at Loguetown.
Completely convinced that all pirates were evil, Smoker needed to witness Luffy's heroism firsthand in order to side with him. Although he hasn't had much presence in the story recently, Smoker was so willing to protect the Straw Hats that he even stood up to Doflamingo on their behalf at the risk of his own life.
9 Eustass Kid Didn't Care About Saving Anyone
Eustass Kid was a textbook example of an antihero. Known for high crimes throughout the Grand Line, he did not care about almost anyone and behaved much more like a conventional pirate than Luffy did. Despite this, Kid's goals often aligned with Luffy's.
This prompted them to work together when defeating Big Mom and Kaido, even if Kid promised that they did not have an actual partnership. Based on the care and mindfulness he has toward his first mate, Killer, Kid also has a soft spot for the members of his crew.
8 Nico Robin Had A Dark Past
Despite being one of the crew's more kindly members, Nico Robin had a dark past. The former right hand of Crocodile's Baroque Works agency, she only joined the Straw Hats out of a sense of desperation.
Robin also conducts herself differently than other members of the crew, calmly iterating the most dire possible situations and even snapping the neck of one of Eneru's high priests. To make matters worse, she publicly tortured and humiliated Franky into joining the crew, an aspect of her character which often goes overlooked.
7 Lola The Proposer Dabbles With Human Shadows
At first, Lola the Proposer might seem like a banal woman with no controversial qualities. However, her kindly exterior belies the darker aspects of her nature. For example, she stole Gecko Moria's shadows and used them to enhance Luffy. In this regard, she is willing to deign the same lengths he is just for a chance to win.
Moreover, Lola is Big Mom's daughter who later traveled with Bege's crew. Considering these strong ties to one of Luffy's worst enemies, such origins cannot be overlooked when considering whether to trust her or not.
6 Kuma's Life Was Tragic
At first, Kuma was introduced as a staunch member of the Warlord program. Without any compassion or humanity, it seemed as if he was simply a mindless enforcer of the World Government. However, it quickly became clear that he was much more.
Through using the Paw-Paw Fruit on Luffy's crew, he whisked them to safety when they otherwise would have been captured by Kizaru. Luffy later realized Kuma's true allegiance to the Revolutionary Army. By that time, however, his mind and body were broken beyond repair.
5 Ashura Doji Was A Brutal Mountain Bandit
Out of all Scabbards, Ashura Doji was easily the most complex. The former leader to a group of mountain bandits, he initially refused Oden's wishes and even attacked him. Doji only changed his mind after realizing Oden's potential, which transformed his territory into the blossoming metropolis it was at Wano's peak.
Despite his origins as a selfish robber, Doji showed growth when sacrificing himself for the sake of his comrades against Kanjuro. Although his loss was one of Wano's most poignant moments, it illustrated just how profoundly Oden's teachings impacted his life.
4 Denjiro Posed As An Enemy For 20 Years
In the beginning, Denjiro seemed like just another heartless villain under Orochi's employ. He ruthlessly kept the peace, cutting down all adversaries and allegedly even Hiyori herself. However, when the Onigashima raid fully commenced, Denjiro's true allegiances became clearer.
He had been masquerading in Orochi's court for twenty years just so he'd have the opportune moment to kill him later. In this regard, Denjiro is a polar opposite of Kanjuro since neither faction was aware of his true allegiance until he personally revealed them. Denjiro's betrayal saved Kin'emon's entire operation.
3 Trafalgar Law Was A Cold Analyst
Trafalgar Law first met Luffy at Sabaody. Despite being a relatively gallant person who cares for the innocent, he has many anti-heroic qualities that fans overlook. For example, his initial mission was driven by revenge for his late guardian, Corazon.
Additionally, Law has no problems with mutilating opponents and even flagrantly killed Vergo at Punk Hazard. He was also a member of the Seven Warlords program, making him a former ally to the World Government over the series' two year time skip. Were it not for Luffy, Law might have even been responsible for Kin'emon's death.
Although an unquestionable ally to Luffy, Zoro is far less compassionate in general than other members of the Straw Hat pirates. For example, he has no qualms with striking an enemy down and yearning for more opponents to rip through. He is also not above killing targets, as seen through his confrontation with a local ruler at Wano.
This quickly gave him the reputation as a ronin, though people responded to him as if he were a wandering serial killer. Nonetheless, Zoro did not mind his defamation much since the opinions of others are mostly irrelevant to him.
1 "Big Gang" Bege Was A Criminal & Assassin
"Big Gang" Bege was a member of the Worst Generation who made an alliance with Big Mom. Though forcing Sanji to attend her wedding and serving her for a time, Bege was not actually a mindless drone. Instead, he waited for the opportune moment to betrayal his client and kill her.
He thought that by assassinating Big Mom, he could increase his reputation on the high seas considerably. This made him Luffy's most valuable ally in the Whole Cake Island arc, especially since he knew what the Charlotte family was up to at virtually all times.