— Zoro !! (ZoSan AU!)

Everyone thinks that Zoro hates Sanji, but that's a lie. He has a love-hate relationship with the cook, but he doesn't entirely hates Sanji. He doesn't like the way Sanji treats women because it's different from men. Sanji treats women with affection, flirts with them, and refuses to fight with them, even if necessary (and if he fights, he doesn't hurt them, not a single scratch, nothing.) But with men? Sanji often treats them with ignorance, or without much special manner. He treats them differently, and Zoro finds this annoying because he thinks that gender is not what defines the way we should be treated. Zoro is always shown to compete with Sanji, getting into fights with each other over petty matters, often at inopportune moments. They had some early disagreements with each other during the Arlong Park Arc on how to deal with Nami's alleged betrayal, but their back-and-forth relationship officially began on Little Garden when the two competed in a hunting expedition. Their rivalry extends to Sanji's cooking, as Zoro rarely acknowledges its quality, usually just calling it "okay". Zoro also has a habit of insulting Sanji when he is flirting with Nami or Robin. Both have common insulting nicknames they call each other. Zoro never calls Sanji by his name, usually calling Sanji "dartboard brow", "ero-cook", or "dumbass cook" while Sanji often calls Zoro "marimo" (mosshead), "shitty marimo", or "shitty swordsman". This has gotten to the point where Zoro has never actually referred to Sanji by his name.[32] After their return to Sabaody Archipelago after training for two years, Zoro mocked Sanji arriving later to him by referring to him as "Number 7" and himself as "Number 1". Despite their comical fights and rivalry, they have an unspoken trust and care between them they would never admit to. In fact, the two warriors understand each other better than other crewmates. Zoro's trust in Sanji's strength and character can be seen multiple times.

Born in the East Blue, Zoro is the son of Tera and Roronoa Arashi, the grandson of Shimotsuki Furiko and Roronoa Pinzoro, and the grandnephew of Shimotsuki Ushimaru, making him a descendant of both the Shimotsuki Family of Wano Country and the legendary samurai, Shimotsuki Ryuma. As a master of Three Sword Style, a swordsmanship style which he created during his childhood training in Shimotsuki Village, Zoro is one of the three most powerful combatants of the Straw Hats, alongside Luffy and Sanji, who is referred to as the "Monster Trio". His dream is to become the greatest swordsman in the world, to honor a promise he made to his deceased childhood friend and distant cousin Kuina.

In addition to his infamy as one of the Straw Hats and as a former bounty hunter, his sizeable bounty upon arriving at the Sabaody Archipelago caused Zoro, along with Luffy to be included among the eleven "Super Rookies", pirates who simultaneously reached the Red Line with bounties of over Beli 100,000,000 shortly before the Summit War. He, the other ten Super Rookies, and Marshall D. Teach would go on to be referred to as the "Worst Generation."

Zoro gained his first bounty of Beli 60,000,000 after the Arabasta Arc. It later increased to Beli 120,000,000 after the Enies Lobby incident, then again to Beli 320,000,000 after the Dressrosa Arc. Following the Raid on Onigashima, his bounty was increased to Beli 1,111,000,000.

Zoro is a tall, muscular young man with lightly tanned skin. He always carries his three swords along with him, bundled up with a green haramaki over his right hip, allowing him to easily draw them with his left hand. Of the three swords he has on his person, he has always been seen carrying the Wado Ichimonji, while his other two swords have varied over time due to them being destroyed and subsequently replaced with progressively better ones. Although his right hand is usually seen resting over them, he can also use this hand to pull his swords out before sitting down. He has three identical gold earrings on his left earlobe. Zoro normally keeps a black bandana tied around his left bicep and ties it around his head when he is fighting seriously against an opponent.

Zoro's body is covered with scars from his many battles, most notably the massive scar stretching from his left shoulder to his right hip that he acquired during his loss against the world's greatest swordsman, Dracule Mihawk, at Baratie. His other visible scars are the scars he inflicted upon his ankles in a desperate attempt to free himself from Mr. 3's Tokudai Candle Service Set by trying to cut his feet off at Little Garden. After the timeskip, he gained another scar over his left eye, obtained through unknown means.

Zoro's other remarkable feature is his cropped green hair, which Sanji often teases him about by calling him "marimo" (moss-ball, moss-head in the VIZ manga and Funimation adaptations) due to its resemblance to one.

Similar to most of his male crewmates, Zoro has the same outfit throughout most of the series. Before the timeskip, he would consistently wear a white short-sleeved henley shirt, a green haramaki, black pants, and black boots. However, only Zoro's shirt varies from time to time in the arcs.

During the Loguetown Arc, Zoro acquired Sandai Kitetsu and Yubashiri to replace the two conventional katanas that were broken by Mihawk in the Baratie Arc.

During the Drum Island Arc, Zoro was bundled up for the winter island but later stripped down after a foolish choice to swim in the frigid water on the island. He remained shirtless and barefoot at the beginning of the arc after getting lost from the Going Merry and left unable to redress himself until he stole a parka from a man in Wapol's army, which was a hooded, forest green parka with a light green sash and white fur on the cuffs, hood, and hem, as well as a pair of boots.

Zoro usually maintains a very stern, serious, and distanced personality, but often loses his temper in a goofy and exaggerated comical style. It would seem however, that this anger is the only emotion that Zoro often feels comfortable showing. Outside of situations where he feels confident in battle, he tends to smile or laugh the least out of the Straw Hats and rarely fools around with the rest of the crew and likes to distance himself more to sleep or train. In fact, his defeat at the hands of Dracule Mihawk and subsequent vow to Monkey D. Luffy is the only time since his friend Shimotsuki Kuina passed that Zoro has been seen crying in the series.

Even in moments that are particularly tough on the crew and would warrant sadness, Zoro chooses to maintain a quiet solemnity rather than outwardly express his emotions. He has been shown to believe to a degree that these emotions can hinder his judgement as a swordsman: when Ohm asked him if he was out for revenge upon discovering Tony Tony Chopper wounded and unconscious, he replied that he does not like to fight for reasons like that. Despite this assertion, though, he cares deeply for his crewmates and wishes to protect them at all costs, telling Ohm that in spite of his preference for fighting without a motivation he can feel one coming on.

Although Zoro cares for his crew, he can also come off as a very blunt and cold person, especially when he is trying to get his point across.

Zoro has devoted his life to becoming the world's strongest swordsman. Even before joining the crew, he was well-renowned for his outstanding abilities and accomplishments in battle. His skills drastically improved after becoming the combatant of the Straw Hat Pirates and entering a two-year training period under the "Strongest Swordsman in the World", Dracule Mihawk.

By the time he met Luffy, Zoro had established himself as a fearsome bounty hunter in the East Blue, so much so that Koby had heard he was a "demon in the form of a man". His accomplishments in hunting pirates were significant enough to earn him the epithet of "Pirate Hunter", which he remains known for even after becoming a pirate. After his crushing loss to Dracule Mihawk, he vowed never to lose again.[22] Since joining the crew, Zoro has defeated several mighty adversaries (most of whom are fellow swordsmen).

Alongside Luffy and Sanji, Zoro is considered one of the Monster Trio (怪物三人組, Kaibutsu San-ningumi?) of the Straw Hats due to his strength. In some instances, he has even been mistaken as the leader of the Straw Hats due to his more extensive reputation; onlookers have also wondered how he could not be the captain after seeing demonstrations of his power. During the crew's journey, Zoro has come to possess some of the most legendary swords in history and has used them to both improve his skills and develop the most devastating attacks.

Zoro was the second Straw Hat to receive a bounty, and for much of the crew's existence, his bounty has been the second highest. Zoro was identified as a Super Rookie after obtaining a bounty of Beli 120,000,000 before reaching the Sabaody Archipelago; he was only one of two non-pirate captains (alongside Killer) of the "Worst Generation" to have that distinction.

Weaker people are easily intimidated by Zoro, as Koby remarked that he had a "demonic aura" at Shells Town even as he was tied up and starved of food for over a week.