Captain Buggy, also known as Buggy the Star Clown, is a pirate who begins his journey as a minor antagonist in the East Blue before rising through the ranks to become one of the most influential and unlikely powers in the world. His background is rooted in the legendary era of piracy, as he was once an apprentice on board the ship of the late Pirate King, Gol D. Roger, serving alongside his future rival, Shanks. During his youth on the Oro Jackson, Buggy and Shanks were known for their constant bickering over trivial matters. A pivotal moment occurred when the crew acquired a Devil Fruit. Intending to steal and sell it for profit, Buggy hid the fruit on his person, only to be startled by Shanks and accidentally swallow it, gaining the powers of the Chop-Chop Fruit but losing the ability to swim forever. This incident also led to him losing a treasure map he coveted, creating a deep-seated grudge against Shanks that would last for decades. After Roger's execution, Buggy refused Shanks's offer to join his crew, choosing instead to form his own pirate crew and pursue a life of treasure hunting in the East Blue.

Buggy's personality is a complex mixture of grandiosity, cowardice, and theatrical showmanship. He is profoundly arrogant, egotistical, and obsessed with treasure, fame, and being feared by others. His speech is frequently peppered with the word "flashy," as he believes all his actions and schemes should be conducted with great spectacle. Despite his grandiose claims of one day becoming the Pirate King, his primary method for achieving power is not through personal combat training but through recruiting strong subordinates and capitalizing on misunderstandings. He is pathologically sensitive about his large, red nose, often mishearing innocent conversations as insults and lashing out violently. While he can be cruel and selfish, treating his crew as disposable when he first appears, he is ultimately a survivalist. His defining trait is a combination of extraordinary luck and an uncanny ability to fail upwards, where his selfish and cowardly actions are consistently misinterpreted by the world as acts of genius or bravery, leading to ever-greater fame and authority.

Buggy's primary motivation is the acquisition of material treasure, with Captain John's legendary treasure being a long-standing object of his desire. He is driven by a desire for revenge against Luffy, who defeated him in their first encounter, and against Shanks, whom he blames for his Devil Fruit curse and lost treasure map. As the story progresses and his reputation inflates due to events beyond his control, his motivations shift to maintaining his newfound status and wealth. When presented with the opportunity, he is easily swayed by the idea of taking down the world's strongest pirates to claim glory for himself, though his nerve often fails him when faced with actual danger. His role in the story is unique, transitioning from a direct antagonist to a recurring comedic foil and a wildcard element in the world's political landscape. He is a catalyst for chaos in the Impel Down prison break and the subsequent Summit War of Marineford, where his past as a Roger Pirate is accidentally revealed to the world, earning him a fanatical following among dangerous criminals. This leads to his appointment as a member of the Seven Warlords of the Sea, a position he uses to found a mercenary organization called Buggy's Delivery. After the Warlord system is abolished, he is publicly named the leader of the Cross Guild, an organization founded by his former enemies Crocodile and Dracule Mihawk, which results in the world government naming him one of the Four Emperors of the Sea, placing him among the most powerful pirates in the world despite his personal weakness.

Buggy has several key relationships that define his path. His relationship with Shanks is foundational; once like brothers, their parting was filled with resentment on Buggy's side, yet they share a deep history and have occasionally cooperated in times of crisis, such as during the Marineford battle. He forms a begrudging alliance with Monkey D. Luffy, who defeated him but whose actions in Impel Down inadvertently led to Buggy's rise to power. His crew consists of his original loyal subordinates, Mohji and Cabaji, his powerful ally Alvida, and the former Baroque Works agent Galdino. However, his most significant following is the hundreds of escaped Impel Down prisoners who revere him as a legendary figure. In the Cross Guild, he is a terrified figurehead, constantly bullied and threatened by the vastly more powerful Crocodile and Dracule Mihawk, who keep him as a puppet leader to attract attention away from their own operations.

Buggy's character development over the series is less about personal growth and more about the widening gap between his perceived power and his actual abilities. He begins as a petty tyrant in the East Blue, is humbled by defeat, and spends much of the story as a prisoner or a struggling captain. His experiences in the high-stakes environment of Marineford do not make him braver, but they do sharpen his survival instincts and his talent for leveraging chaos. By the time he becomes an Emperor, he has been pushed so far by the abuse of his Cross Guild partners that he has a rare moment of genuine resolve, declaring his intention to seriously compete for the One Piece, marking a potential turning point where he might finally embrace the role the world has thrust upon him.

In terms of abilities, Captain Buggy possesses the powers of the Chop-Chop Fruit, a Paramecia-type Devil Fruit that grants him complete immunity to slashing attacks, as his body simply separates around any blade. He can voluntarily split his body into multiple pieces, levitating and controlling these parts independently. This allows for unique offensive and evasive maneuvers, such as attacking an opponent from behind with a detached hand or floating his head out of harm's way. However, his feet must remain on the ground, and his body parts have a limited range from his primary body. Beyond his Devil Fruit, Buggy is an inventor, having created the Buggy Ball, an exceptionally powerful, city-destroying cannonball, and its smaller, hand-held version, the Muggy Ball. He is also proficient with knives and daggers, often wielding several at once. Despite his incredible career and survival through numerous battles on the Grand Line, Buggy is physically one of the weakest prominent pirates. He relies almost entirely on his Devil Fruit's unique defense, his cunning, his charisma, and his phenomenal luck to survive encounters with far more powerful foes.