Classification
The majority of vampires that exist in King's multiverse consist of a standard type. These standard vampires exist in at least three facets of King's multiverse: All-World; the fictional setting of 'Salem's Lot and works related to it; and the "real" world.
All three types of vampires drink blood to survive. While they are immune to blood-borne diseases, they can pass them on to their victims. Due to this, in King's multiverse vampires were instrumental in causing the AIDS pandemic in the 1980s.
Most also seem to require being "invited" into a particular area or building by the proper "owner" of the territory. Once invited, they seem to be able to come and go as they please, even if their invitation is verbally revoked.
Read more about this topic: Vampire (Stephen King)