Life Virus

The Life Virus, known as Dream Virus (ドリームウィルス) in Japan, is the final boss in the games MegaMan Battle Network, MegaMan Network Transmission, and Rockman EXE WS. It also appears in the anime MegaMan NT Warrior as a malfunction of one of Dr. Hikari's new inventions.

MegaMan Battle Network
In the game the Life Virus was the final boss of MegaMan Battle Network. It was created by Wily, who used the four elemental programs to create it. Wily was going to put the virus into a rocket and have it destroy the planet by infecting and destroying the cyberworld. Lan and MegaMan intervened at the last moment and deleted the virus. It lives on however, in the form of the Dream Aura chip, it's a virus which reside in the Secret Area in MegaMan Battle Network 3.

Rockman EXE WS
In Rockman EXE WS, the Life Virus appears as the last boss of the game. When it is destroyed for the second time it gives MegaMan.EXE the HUB Style.

MegaMan Network Transmission
In MegaMan Network Transmission, the game begins with a scene of MegaMan defeating the virus. He is repeatedly mentioned throughout the game as being revived, and is fought at the end of the game as Life Virus R. He is created by an assistant of Wily, the Professor, and can create duplicates of Navi's fought throughout the game. When fighting, he has an elemental aura which can be destroyed with an attack greater than 100, or with an opposing element chip. The Life Virus can also use all elements. When beaten, his core exposes itself, flying around dropping data balls which can do half health bar damage to MegaMan. Once defeated, the Life Virus is destroyed, and although the doctor threatens to revive a new one, he is arrested.

MegaMan NT Warrior
In the anime the Life Virus showed up in the last ten minutes of the final episode of the second season. It was inside the experimental dimensional area Dr. Hikari had created (creating a multitude of viruses, which Lan and co. defeat) and Lan and co. attempted to delete using water. They failed however and just as it was about to crush them, MegaMan and the other Navis appear and attack it using water chips. MegaMan finishes it off with the Aqua Custom style and deletes it for good. An exact copy of it appears in Axess as the final boss of a video game that Roll plays to attract the attention of a Navi kidnapper that kidnaps strong Navis. She fails, but Chaud secretly helps her and opens a portal that absorbs the virus. It has the exact appearance of the Life Virus, but is most likely completely different.

Rockman EXE Beast
An army of Life Virus appears in two episodes of Beast lead by Zoanoroid GutsMan.EXE for the Gregar's army in an attempt to capture Trill. They also fight off Falzar's Tinhawk army that was lead by Zoanoroid SnakeMan.EXE.

Manga

Megaman NT Warrior

The Life Virus appears in volume 2 of the Megaman NT Warrior series in chapter 4 Battleground Silver Tower when Dr.Wily stole the ultimate program and upgraded the Life Virus with it. Megaman EXE and the whole Anti World Three Team arrived to battle the Life Virus they hit it with their best shots but it was useless against the life aura. The Life Virus didn't just have great defence but also powerful offence by taking out all of the Anti World Three Team in one hit with Meteor leaving only Megaman and Protoman to battle.