Viruses are the main enemies encountered in the MegaMan Battle Network series, usually unleashed upon the city by a villainous mastermind, such as Lord Wily. Viruses are found randomly across the cyberspace, searching for NetNavis and other programs to delete. A NetNavi must have basic Virus Busting abilities to navigate safely on the net, otherwise its actions will be limited. Viruses may leave Battle Chip data upon deletion. This all depends on the virus, and the attack that the virus uses. Most viruses have three variations, sometimes more.