Also Romanized as "vrikolakas" and pronounced with Latinate vowels, the vrykolakas is the Greek equivalent of the vampire. Unlike the popular vampire, which is a living human who becomes a vampire upon being bitten by one, the vrykolakas is an undecomposed corpse that has been possessed by a demon or other spirit. In classical Greek mythology, the revenant is not necessarily evil; often, he or she returns to complete unfinished business with someone who was close to him or her in life. However, later conceptions of the vrykolakas had them taking on the more vicious and brutal characteristics of the Eastern European vampire.

The vrykolakas, though predominantly nocturnal, is not harmed by sunlight, and it is said to frequently emerge during the day. Though it visits houses and calls out the names of the people inside, which is said to be a harbinger of death for the ones called, it could also appear in vineyards, fields and the open highways. It could be sent away if its intended victim challenges them, but often the victim ends up being killed anyway. The nature of the "brutal" vrykolakas is such that it visits destruction first on those who were close to it in life, and then to the community as a whole.

Traditional ways of someone becoming a vrykolakas often involve dishonor of some sort, such as being cursed, committing an evil act (especially against one's family), dying violently, or not being buried. The Greek Orthodox Church's perspective in the first millennium AD is that the reanimation of a corpse was due to the influence of the Devil, but eventually it came to state that such a thing could occur to the excommunicated, the violently killed, or those buried without the proper church rites. Stillborn children and those born on major church holidays were also added to the list of possible future revenants. Those wishing to permanently kill a vrykolakas are best off burning it with fire, as the popularly-known methods of stake and sunlight do not appear to work on Greek revenants, and since Saturdays are days on which it cannot rise and walk, make your next vrykolakas-burning a weekend activity. Bring the kids.