K9 is the name given to four similar robots owned by the Doctor and several of his companions. First appearing in 1977's 'The Invisible Enemy', he was originally created by Professor Marius, a scientist working at the Bi-Al foundation in the year 5000. Given to the Doctor as a present (and because of the fact he couldn't take him back to Earth due to weight restrictions) K9 proved to be both loyal and reliable to the Time Lord. The Doctor would often recreate him after he lent him to companions when they left the TARDIS. In the mod, K9 is a neutral mob that can be tamed by the player and used to travel with and fight the various aggressive mobs, including Daleks, Cybermen and Weeping Angels.