The vampire seems to defy the firm, mutually exclusive categories of being dead or alive. A vampire's biography begins with death. Furthermore, much of the vampire's time is spent as a corpse or corpse-impersonator. But at night, when the living lie themselves down, up rises the apparent corpse with its dangerous cravings. In the twenty-first century new definitional issues related to brain death, life support systems, persistent vegetative states, and the freezing of both embryos and cadavers (cryonic suspension) have blurred the boundaries between life and death. It is also recognized that some structures, such as the mosaic tobacco virus, can exhibit the properties of either a living or nonliving structure depending upon their situation. For much of history, though, it was the vampire who most daringly crossed and recrossed the borders between the living and the dead.

Vampires are sometimes referred to as "the undead" and sometimes as revenants, reanimated corpses that drink the blood of the living to preserve their own existence. Scholars currently believe that the word vampire derives from the Slavic language spoken in Serbia. The consensus is that vampire derives from the Slavic verb "to drink." The term was known in England in the late seventeenth century and entered other European languages early in the eighteenth century. Perhaps surprisingly, this term did not make its way to the supposed homeland of vampires—Hungary and Transylvania—until some time afterward.

The vampire (by whatever name) may have been with humankind since earliest times. In his The Great Mother: An Analysis of the Archetype (1963), the analytical psychologist Erich Neumann suggests that early civilizations had an intensely conflicted attitude toward both the earth and femininity.

Neumann offers many examples of rituals and artifacts to support his belief that the vampire is an ancient and universal symbol of the Great Mother swallowing up her own creations in order to recycle them in new form. However, this dramatic idea remains in need of more evidence for the supposed prevalence of vampirism in the ancient world and does not explain why males have been in the clear majority among vampire ranks (until the twentieth century). Scholars also reject the assumption that vampires are part of all world cultures. Native-American traditions, for example, have their own creatures of the night, such as the skinwalkers (restless spirits of the dead who sometimes make themselves visible), but these do not fit the precise profile of the vampire. A plausible case could be made for a widespread fear of the dead in many cultures, but not necessarily for belief in blood-sucking revenants.

It is clear that vampirism had a secure place in Slavic superstitions for many years before it became a household word with the publication of Bram Stoker's Dracula (1897). The author transformed these folk stories into a dark gothic romance. His leading character was inspired by a character he did not have to invent: Vlad Tepes, a fifteenth-century tyrant who slaughtered and sometimes tortured thousands of people. "Vlad the Impaler" was no vampire, though; he did his terrible deeds while alive and had a hearty appetite that did not include sucking blood. Stoker, using literary license, combined the historical Vlad with vampire legends and added a veneer of Victorian culture. Separating fact from fantasy became increasingly difficult as popular literary and theatrical vampires distanced themselves from their roots in anxiety-ridden folklore. Inquiring minds have therefore been following the trail of the vampire, classifying and explaining as best they can.