The vrykolakas (Greek βρυκόλακας, pronounced [vriˈkolakas]), also called vorvolakas or vourdoulakas, is a harmful undead creature in Greek folklore. It has similarities to many different legendary creatures, but is generally equated with the vampire of the folklore of the neighbouring Slavic countries. While the two are very similar, blood-drinking is only marginally associated with the vrykolakas.
The word vrykolakas is derived from the Slavic word vǎrkolak. The term is attested in other South Slavic languages such as Serbian , ultimately derived from Proto-Slavic vьlkolakъ, see Polish wilkołak, and cognates can be found in other languages such as Lithuanian and Romanian . The term is a compound word derived from вълк (vâlk)/вук (vuk), meaning "wolf" and dlaka, meaning "(strand of) hair" (i.e. having the hair, or fur, of a wolf), and originally meant "werewolf" (it still has that meaning in the modern Slavic languages, and a similar one in Romanian: see ). It is also noteworthy that in the eighteenth century story Vrykolokas by Pitton de Tournefort, he refers to the revenant as a "werewolf" (loups-garous) which may have also been translated as bug-bears, a strange word that has nothing to do with bugs nor bears, but is related to the word bogey, which means spook, spirit, hobgoblin, etc. However, the same word (in the form vukodlak) has come to be used in the sense of "vampire" in the folklore of Western Serbia, Bosnia and Herzegovina, and Montenegro (while the term "vampir" is more common in Eastern Serbia, and in Bulgaria). Apparently, the two concepts have become mixed. Even in Bulgaria, original folklore generally describes the vârkolak as a sub-species of the vampire without any wolf-like features.