Boomer

 Boomer is a virus from the Mega Man Battle Network series. It attacks by shooting a boomerang that travels along the outer walls of the field. It hits every panel except for those in the middle. It is invulnerable until it releases its boomerang as part of its attack, at the end of which it catches the boomerang and is once again invulnerable. Stronger variants of this virus utilize PanelGrab chips, stealing the center panel.

Boomer
 Boomer is a black and purple variant with red eyes and a silver blade.

Gloomer
 Gloomer is a green and blue variant with orange eyes and a silver blade.

Doomer
 Doomer is a purple and green variant with yellow eyes and a gold blade.

BoomerΩ/DoomerEX
 BoomerΩ is a blue and light-blue variant with orange eyes and a silver blade.

BoomerEX
 BoomerEX is a red and gray variant with blue eyes and a silver blade.

GloomerEX
 GloomerEX is a silver and dark-gray variant with orange eyes and a gold-silver blade.