A Vampire is an Undead humanoid of vast necromantic power whose unlife is sustained by consuming the lifeforce of the living, usually but not always in the form of their blood.
Unlike most of the Undead, Vampires retain all of their intelligence and will, and hence all of their ambition and desire. This makes them very dangerous indeed, for they can continue to grow and learn, spending eternity perfecting their skills and honing their plans and schemes.
They can turn the living into new Vampires by first draining them of their blood and then sharing with their chosen their own, tainted blood. 
Though most Vamoires are known for their cold beauty, the Abhorrant Ghoul Kings are degenerate Vampires, believing themselves to be noble kings when they are actually nothing more than vicious scavengers.