Kuroro Lucilfer, also known as Chrollo Lucilfer, originated from Meteor City, a junkyard settlement unrecorded in official documents and home to societal outcasts. Around age eleven, he formed bonds with future Phantom Troupe members Uvogin, Machi, Pakunoda, Feitan, Phinks, Shalnark, Franklin, Nobunaga, and Sarasa. Together they discovered a VHS tape and began creating dubbed film presentations for fellow residents, calling themselves "The Troupe." Their collaborative efforts strengthened relationships through scriptwriting, voice acting, and live performances, with Kuroro often leading. A pivotal tragedy occurred when Sarasa was abducted and brutally murdered; the group discovered her mutilated body in a forest near Meteor City. This event profoundly impacted them, leading to Sarasa's funeral and subsequent discussions about their future. Kuroro then expressed his intent to live as a villain to deter criminals from targeting Meteor City's vulnerable inhabitants. Approximately three years later, around age fourteen, he formally established the Phantom Troupe with six core members, later expanding it to thirteen total members. As leader, he bears the number zero tattoo.

Kuroro possesses a calm, intelligent, and charismatic demeanor, enabling him to unify the volatile Phantom Troupe. He demonstrates deep loyalty to the group, prioritizing its survival over his own life and viewing the leader as expendable for the Spider's collective existence. This loyalty manifests emotionally: he cried upon foreseeing Uvogin's death through a stolen fortune-telling ability and orchestrated a massacre of Mafia members as a requiem for him. Similarly, he expressed visible fury and vowed revenge after Hisoka killed Kortopi and Shalnark. Kuroro is also capable of extreme ruthlessness and mass murder, participating in the Kurta Clan massacre where innocent people, including children, were tortured and killed to steal their Scarlet Eyes. His cold-blooded nature extends to using abilities like Indoor Fish, which consumes victims alive without immediate pain or bleeding. He exhibits strategic manipulation, feigning friendship with Neon Nostrade to fulfill the conditions for stealing her Lovely Ghostwriter ability, showcasing skill in deception and acting.

Kuroro's Nen specialization is "Skill Hunter" (Bandit's Secret), allowing him to steal others' Nen abilities by meeting three conditions: witnessing the ability in action, having the user explain it, and touching their palm to his conjured book. Stolen abilities require the book to be held open to the relevant page during use and vanish if the original user dies; they retain any limitations set by their creators. Key stolen powers include Indoor Fish for summoning flesh-eating skeletal fish in enclosed spaces; Fun Fun Cloth for shrinking or enlarging covered objects; Lovely Ghostwriter for predictive poetry; Black Voice for remote control via antennae; The Sun and Moon for explosive tattoos; Gallery Fake for creating replicas; Order Stamp for animating inanimate objects; and Convert Hands for appearance alteration. He later innovated "Double Face," a bookmark enabling dual-ability activation or freeing one hand for combat. Beyond Nen, Kuroro uses equipment like Ben's Knife (poison-coated), cellphones for Black Voice, and ordinary pens as impromptu weapons.

Physically, Kuroro has black hair, grey eyes, a cross-shaped forehead tattoo, and orb-shaped earrings. He typically wears a dark coat with white fur accents and a golden inverted cross on the back. His spider tattoo bears the number zero, though its exact location varies across adaptations. He ranks seventh in physical strength among the Troupe but compensates with superhuman speed, durability, and combat skill, evidenced by surviving simultaneous battles against Silva and Zeno Zoldyck, decapitating foes with bare hands, and piercing skulls with pens.

Key events involving Kuroro include the Yorknew City arc, where he led an auction heist and lost his Nen abilities after Kurapika imposed a Judgement Chain prohibiting Nen usage or communication with Troupe members. This forced him to seek an exorcist, eventually regaining his abilities. During the Heavens Arena arc, he fought and killed Hisoka using a complex strategy involving multiple stolen abilities and puppet replicas. Hisoka was later revived and began assassinating Troupe members, prompting Kuroro to prioritize hunting him. Most recently, during the voyage to the Dark Continent, Kuroro and the Troupe boarded the Black Whale ship, engaging with Kakin's mafia families to locate Hisoka while navigating internal conflicts. A flashback to their Meteor City origins revealed how shared trauma and loyalty shaped their development, contextualizing their motto: "We accept anything left here, but never take anything away."