Denji is the main protagonist of Chainsaw Man, characterized by his scruffy blonde hair, sharp shark-like teeth, tired eyes, and a lean, scrawny build resulting from severe childhood malnutrition. After forming a contract with his devil-dog companion Pochita, who fused into his chest to replace his heart, Denji gained a pull-cord on his sternum that lets him transform into the Chainsaw Man hybrid. In this form, his head warps into a metallic mechanical helmet with jagged fangs, and enormous, retractable chainsaws rip through his head, arms, and legs

Aki Hayakawa is a tall, handsome Public Safety Devil Hunter in Chainsaw Man defined by his signature black topknot hair, blue eyes, dark suit uniform, and a sword slung over his back. While he initially projects a stoic, mature, and no-nonsense personality fueled by a deeply buried trauma and a vengeful desire to destroy the Gun Devil, he is secretly deeply empathetic, sensitive, and fiercely protective of his comrades, eventually developing a profound familial bond with Denji and Power. In combat, Aki relies on lethal contracts with supernatural entities: he commands the Fox Devil to bite apart enemies, utilizes a nail-like sword from the Curse Devil to execute fatal one-hit kills at the expense of his own lifespan, and uses the Future Devil residing in his right eye to glimpse a few seconds ahead during battle.

Power from Chainsaw Man is a wildly popular Blood Fiend and Public Safety Devil Hunter who possesses the corpse of a young woman, giving her a distinctive appearance marked by strawberry-blonde hair, sharp fangs, red-and-yellow eyes with a cross pattern, and prominent red horns that grow larger and more curved whenever she overconsumes blood. Her primary ability is blood manipulation, allowing her to solidify and weaponize her own blood—or the blood of others through direct contact—into highly lethal constructs like hammers, spears, and axes, while also enabling her to consume blood to heal rapidly and tap into a monstrous four-armed true Blood Devil form.

Introduced in the dark fantasy series Chainsaw Man, the Angel Devil (often simply called Angel) is a unique, high-ranking Public Safety Devil Hunter who embodies humanity's fear of angels. Visually, Angel resembles a young, beautiful, and androgynous male with shoulder-length reddish hair, a floating golden halo, and large white wings on his back that are durable enough to act as bulletproof shields. His core, devastating ability allows him to automatically absorb the lifespan of any human he touches; he can then manifest this stolen time through his halo into powerful, supernatural weapons, like swords and spears, whose strength scales with the number of years sacrificed.

Beam, the fan-favorite Shark Fiend from the manga and anime series Chainsaw Man, is a highly eccentric. Physically, he features the body of a muscular young man clad exclusively in swimming trunks, but the top half of his head is replaced by a pointed shark snout and dorsal fin with razor-sharp teeth and no visible eyes. While generally antisocial, erratic, and aggressive toward others, his absolute "ride-or-die" loyalty means he will eagerly throw himself into harm's way, even offering up his own blood to revive Denji at his own expense. As a fighter, Beam possesses incredible physical durability—capable of tanking point-blank explosions—along side his signature trait of intangibility, which grants him the specialized ability to literally swim through solid objects like walls, floors, and concrete buildings as if they were water. He acts crazy when he’s tired, he acts crazy in general.

In the dark fantasy series Chainsaw Man, Reze is a teenage Soviet assassin of slender build with shoulder-length dark purple hair and feline-like emerald-green eyes, who initially hides a transformation pin in her neck with a black choker. As a Weapon Human fused with the Bomb Devil, her hybrid transformation turns her head into an airship-shaped atomic bomb and wraps her body in dynamite sticks and bomb fuses. Her immense combat capabilities allow her to generate catastrophic explosions from her body, use those blasts to fly, effortlessly regenerate from fatal wounds, and showcase superhuman strength and speed. Though she initially presents herself as a gentle, clumsy, and flirtatious cafe waitress to seduce Denji and steal his heart, her true persona is a highly trained, calculated, and lethal killer

Makima is the primary antagonist of Part 1 of Chainsaw Man, hiding her true identity as the Control Devil behind the appearance of a beautiful human woman in her twenties with long, pale-auburn hair kept in a loose braid and striking yellow eyes containing multiple red concentric rings. Usually seen in a sharp, professional Public Safety uniform consisting of a white shirt, black tie, and fitted trousers, she projects a calm, gentle, and highly charismatic persona. However, this facade conceals a ruthless, cold-hearted, and Machiavellian manipulator who views all humans and lesser devils as "dogs" meant to be controlled to achieve her ultimate goal of creating a pain-free world—a fixation driven deeply by her obsessive infatuation with Pochita. As one of the most powerful entities in the series.