Zero.EXE

"You are warriors, fighting for peace in the Cyberworlds... I, on the other hand, spread evil by simply existing... So you must be here to delete, that is, bust me. Right? (Lan: ...) But I have no pleans to disappear just yet. I'm ready to fight you!"

- Zero.EXE

"... You know, I didn't ask to be born as a virus. But I want to know one thing. This world where I was born, and its people. And you, the humans and Navis, you see me as evil incarnate, spreading poison. So there's nothing to be concerned about. It's just the way it is."

- Zero.EXE

Zero.EXE is one of the antagonists of the Mega Man Battle Network/NT Warrior series, though he can join the side of good and be a good NetNavi depending on a player choice in the game.

Mega Man Network Transmission
He was originally programmed by Lord Wily to destroy net society by infecting all NetNavis. Lord Wily never ended up using it, and it was eventually discovered by the Professor, who used him as Wily had originally intended. While this was part of his goal, he mainly did this to gain resources to create the Life Virus. In addition, while he is technically a virus, he seems to appear, think, and act similar to NetNavis, and in one route in the game, he can actually be a Navi. He appears as a boss late into the game for Lan and MegaMan to defeat. While he is aware that he gained sapience, he still struggles to escape his basic programming with which he was created. After the battle, he acknowledges that he was created as an evil virus and that he spreads evil wherever he goes. He accepts his fate as just the way things are. However, Lan and MegaMan feel sympathy and hesitate to delete Zero, seeing that he is indeed more than a mere virus. However, Chaud and ProtoMan intervene, insisting that he must be deleted for the greater good. At this point, one of two things happens. If Zero's source code was not found, then Zero is deleted then and there. If it is found, then Yurichio Hikari interrupts, claiming that with his source code, he can be turned into a fully sentient Navi. This prompts Zero to ask why anyone would be kind to him, and while he does not fully understands, he accepts the offer to become a Navi as opposed to a mere virus or deletion. While this transformation does take his ability to spread the Zero Virus away by containing it, he does still control the infections that have already been spread. Either way, at this point, the Professor calls to announce his true plans. Zero can still help, if the player found his source code, by noticing that a large portion of his data is with the Professor, which lets authorities track him down and arrest him. He is able to wander the Cyberworlds, albeit under supervision. In either case, this is his only in-game appearance.

Mega Man NT Warrior
Unlike his game counterpart, his anime counterpart was created by the Professor, built by leftover data from the Super Cybeast. He is treated as a mere tool to be used by the Professor, which he despises. Despite being a virus, he feels himself to be more sapient than a mere tool, and longs for this sense of freedom. While witnessing ProtoMan's devotion and commitment to Chaud during a raid on the Professor's base, Zero decides to disobey his master and go off on his own. Later, GutsMan accidentally bumps into Zero. This prompts Zero to attack a nearby Energy Center. While MegaMan appears to attack Zero, he reveals that he only did it to give a gift to GutsMan, having felt a different Navi's hand for the first time. After this, he joins the side of the protagonists. Later is a battle between MegaMan and a copy of Zero, known as Zero One. Unlike Zero, Zero One is devoid of emotions, as the Professor saw that Zero's emotions lead to his betrayal. He hesitates to help at first, though is lated coaxed into it. He eventually sacrifices himself as he pins his copy down and his copy self-destructs.