Number Zero commands the Western Bloc's Zero Zero Organization intelligence agency during an extended cold war. His true identity is concealed from subordinates and outsiders, preserving an enduring aura of secrecy across all depictions.

He directs operations involving cyborg agents, including primary operative Mylene Hoffman (009-1), typically displaying calm authority during mission briefings. Interactions with agents are mainly professional, though rare instances suggest a possible paternal dynamic with Mylene Hoffman. One documented scene implies potential personal interest through its visual framing.

His leadership entails deploying agents for espionage, sabotage, and assassination missions against the Eastern Bloc. Decision-making prioritizes organizational objectives, sometimes requiring morally ambiguous operations like eliminating perceived threats, including children. During the anime series climax, he demonstrates operational flexibility by retroactively classifying Mylene Hoffman's unsanctioned mission to rescue mutant children as official, preventing her rogue agent status.

Adaptations preserve his core traits without expanding his background or personal history. The live-action film *009-1: The End of the Beginning* introduces no new narrative elements about his origins. His role remains strictly confined to organizational command across all official media, showing no evolution beyond this function.

Visual representation varies minimally: traditional depictions show an older male figure, while the live-action film presents a younger interpretation, both maintaining his fundamental authority and narrative purpose.