Vampires are a type of undead that need to feed on the essence of life in order to survive. They are the only type of undead that have both body and soul, though their soul is damaged beyond repair. Different vampires feed off of different things, from blood to magic to memories, as long as it bears the mark of life can sustain them. This is where similarities beween vampires ends, as the species can vary greatly, from the civilised Higher Vampires to the beastly Chupacabra.
In some cases, vampirism can spread through the blood, similarly to lycanthropy. Another similarity they share is their adversity to pure materials, particularly holy water and silver. Vampires have other weaknesses, but these weaknesses differ from species to species.