"These hellspawn were first summoned by the sorcerer Horazon to guard his Arcane Sanctuary. Possessed of the demonic fire that fuels Hell itself, they cast vicious fireballs at their victims to consume the living flesh from the bones they covet to conduct their dark experiments. Their touch is filled with the cold unlife of the grave that will slow even the healthiest of adventurers."(src)
Vampires are undead creatures.
Vampires are found in Diablo II in the first three acts. Vampires can cast several Sorceress skills to destroy their enemies: Fireball, Fire Wall, Meteor; as well as their own skill, a life stealing missile attack. Their melee attack has a chance to cause cold damage. They will occasionally run away when severely damaged.
The Vampire model had been designed by 1999.