Vampires appear throughout Stephen King's fictional multiverse. They appear in the novels 'Salem's Lot, Wolves of the Calla, Song of Susannah, and The Dark Tower; the short stories "One for the Road", "The Night Flier", "Popsy", and "The Little Sisters of Eluria"; and are mentioned in a number of other stories. Marvel Comics' The Dark Tower: End-World Almanac includes a detailed entry on their categorization.
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.
Type One vampires are "lesser demons", the last remnants of the Prim (magical beings who predated creation and dissolved when Gan made the multiverse). Although humanoid in shape, they are extremely deformed, with an emaciated appearance; enormous, inch-long teeth that force their mouths open; and large amounts of tumors, body hair, and other physical defects. Their bodies are adapted for the seeking and consuming of blood: their noses are attuned to smell even traces of blood from long distances, their teeth are built for piercing and draining skin, their stomachs can expand to hold as much as half their body weight in blood, and their tongue is long and prehensile, and can produce anticoagulants to apply to bites on victims.