In the Mega Man Battle Network series, the common virus is called Mettaur.
Mettaurs are small cybernetic enemies wearing hard hats and carrying pickaxes. Their signature attack is a shock wave sent across the battlefield, usually after they briefly emerge from their helmets. The helmet also gives them a defensive rhythm: many Mettaurs hide beneath it, becoming temporarily immune to ordinary attacks until they expose themselves.
The name is derived from the “Met” enemies of the classic Mega Man games, which also wear helmets and often use pickaxes or similar attacks. In Japanese, the Battle Network enemy is known as Metall, or Metall in romanized naming, while English releases use Mettaur. This localization difference can cause confusion, but Mettaur is the canonical English answer.
Mettaur is especially notable because the species appears throughout all six mainline Battle Network games. Variants such as Mettaur2, Mettaur3, and MettaurΩ add stronger versions, while related Battle Chips include Met Guard and Shock Wave. Swordy, Canodumb, and Blox are other virus types, not alternate names for Mettaur.