Vamdemon is an Undead Digimon whose name is derived from "Vampire" and "Demon" and whose English name, Myotismon, is derived from the Greater mouse-eared bat. As the king of Undead Digimon, it was resurrected through the dark arts and obtained mighty powers. Originally a brutal computer virus which destroyed the computer data it absorbed, it possessed the ability to revive the destroyed data as malignant computer viruses. As the owner of an extremely cruel and cunning personality, it is exceedingly difficult to destroy this Digimon. However, it cannot demonstrate its powers outside of the night, and its power is cut in half during the daytime.

Vamdemon is one of the main villains in Digimon Adventure and a 1 episode only villain in Digimon Ghost Game and Digimon Beatbreak. He is also a villain in the manga series Digimon Adventure V-Tamer 01, and the Ultimate evolution of Kaito Shinonom's digimon partner in the game Digimon Survive.