In the west, we tend to categorize everything. We try to come up with rules and regulations that define what something is, sometimes to desperate lengths and great frustration when something just doesn't fit.
Mythical creatures are no exception. We view the vampire as a blood drinking undead human, and a werewolf as a living human that can take a wolf-like form and ravage the population like an animal. In Eastern Europe, the homeland of most folklore relating to the vampire and werewolf, these lines can become hopelessly blurred, and the creatures can become almost the same.
Take the vrykolakas, the Greek version of the Vampire. While most vampire legends tend to involve drinking human blood as part of the mythos, in this case, it does not. If you speak with a mystic, they will tell you the vrykolakas comes into being simply after living a sacrilegious life, or after an excommunication or burial in ground that was not consecrated, or most ominously eating mutton that had been previously tasted by a werewolf. Speaking of, even a werewolf couldn't be safe from becoming a vrykolakas, if you killed the greek werewolf, he could come back as a cross between a vrykolakas and a werewolf! The fusion of these two creatures in Greek culture is one of the most fascinating aspects of the vrykolakas-style vampire.
Once in existence, the vrykolakas would not bite the neck of his victims to draw blood, rather it would cause epidemics of disease by simply walking around town. It would knock on doors, only to disappear if the person answered on the first knock, but that person would then be condemned to death soon after and would become a vrykolakas themselves. To this day in certain parts of Greece, people do not answer the door until at least the second knock.
Even poltergeist activity is blamed on the vrykolakas, though that may be off-base in that the poltergeist is likely a completely different phenomenon. Sleep paralysis is also pinned on the legend, as a sort of fusion between the concept of the incubus and the Balkan vampire's penchant for killing victims by sitting on their chest. Methods of dispensing with a vrykolakas are much the same as the western concept of the vampire; impaling. But there are other methods for this creature that work just as well, such as cremating the suspected corpse and even a standard exorcism is said to do the trick.
The vrykolakas is just one of many different variations of legendary undead creatures that resemble the western concept of the vampire. Perhaps, when dealing with folklore, we should take this into account. Imagine a film based on the vrykolakas instead of the western vampire, with powers greatly expanded from simple blood-drinking and wandering in the night.