Zero.EXE

Zero.EXE (ゼロ.ＥＸＥ) is a character in the MegaMan Battle Network series of video games and the MegaMan NT Warrior (Rockman EXE) anime. He is the first character in the Battle Network series based on a character from the Mega Man X series.

Game
Zero was originally a virus created by Dr. Wily and World Three in an attempt to bring down the internet by infecting the NetNavis that inhabit it. He is a boss in MegaMan Network Transmission, but, given that You perform certain acts in the game, Zero will be reborn as a genuine Navi. This indeed did occur, with MegaMan.EXE and ProtoMan.EXE defeating him in battle. Dr. Yuichiro Hikari installed a program which eviscerated his virus status and allowed him to thrive at the Science Labs. Zero now explores the internet under supervision of said officials. In MMBN 6 if you collect all cards deafeat bass BX and falzar/gregar sp you can fight zero in falzar and X in gregar in the graveyards secret path...

Anime
In the anime, Zero, similar to his game counterpart, is a virus who serves evil, though he was created by the Professor instead of Wily. He was born of the leftover Beast Factor data of the Super Cybeast (Super Cyber Beast) Gregar, which was thought to have been destroyed at the end of Beast. He was to supervise the resurrection of Grezar through infection of the net, gathering energy, and spreading the Beast Factor to regular viruses. In seeing ProtoMan's devotion to his operator during a raid of the Professor's hideout, Zero chose to disobey his master's orders, and left him to die in the destruction wrought by the Super Cybeast's premature awakening.

GutsMan.EXE mistakenly bumps into Zero later, thinking him to be just another Navi. The virus, having felt someone else's hand on his own for the first time, attacks the Energy Center. MegaMan intervenes, only to discover that Zero's intention is to retrieve a birthday present for GutsMan. Thus he joins MegaMan as one of his partners, having found the "companionship," "friendship," and "heart" that he sought during his absence.

During the subsequent battle with the Professor's new heartless soldier, Zero One, the virus is reluctant to aid MegaMan in the fight as he was created without such a program. GutsMan, however, urges him to help. After taking a hit for MegaMan, Zero retaliates with force. In an act of gratitude for the kindness they have shown him, Zero substantiates both himself and Zero One near the Professor's airship, just as his copy self destructs.

Personality
Zero is nearly identical to his X series counterpart. He completes tasks as given to him, does not go against higher command and seems quite soft-spoken. After becoming a Navi, he gains a positive outlook on his existence, looking out for the greater good and coming to understand things such as friendship and trust, which were previously foreign to him.

In the anime, Zero is an obedient servant. He does not speak for the most part while working for the Professor (his breathing is similar to that of Darth Vader from Star Wars), but gradually develops a yearning for freedom. He does not appreciate being called a mere "tool," and feels that, despite being a virus, he has "will." Zero would eventually learn the importance of friendship, finally seeing what Navis possess that viruses do not, and developed a newfound desire to be around others. The sadness that MegaMan and GutsMan feel for him when he is injured leads him to sacrifice himself to save them.

Trivia

 * The fact that Zero.EXE was created by Mr. Wily is similar to his original counterpart, that Zero was the final creation of Dr. Wily before his passing.
 * Zero's initial status as a Virus could be a nod to the Zero Virus, the progenitor of the Maverick Virus in the X-series.
 * Zero.EXE is one of three NetNavis based off of a character from the Mega Man X series. The other two are Iris and Colonel, whose counterparts are Iris.EXE and Colonel.EXE respectively.