One of the traditional Greek curses was "May the earth not receive you!" This was the case with the vrykolakas (plural vrykolakes). Instead of decaying in the grave, the flesh swells up and take on a 'drum-like' texture (this is the term all my references use).
The vrykolakas is a little different from the 'regular' vampire in that you rarely read about one drinking blood. They prefer milk, lots of it, fresh from the goat. Although the vrykolakas is classified as a vampire, I could see where a comparisons to the zombie could also be made. Vrykolakes are fairly ugly, and property damage, disease spreading, and rending people seem to be their preferred activities.
A person can become a vrykolakas after death by being very wicked in life or by being excommunicated from the Greek Orthodox Church (according to John Cuthbert Lawson, the Church alternately boasted and disavowed this claim). Eating meat previously gnawed on by a wolf/werewolf put you at risk (the werewolf in life/vampire in death trope). Violating various taboos or being cursed by a parent were also potential causes, as was having your baptism screwed up (back to the priests again).
Lawson claimed that Greeks could tell which way a vrykolakas came into being by a using handy color-code system from the Church of St. Sophia at Thessalonica, reproduced here:
He who has left a command of his parents unfulfilled or is under their curse has only the front portions of his body preserved.Wouldn't that make a good flash card for a monster-hunter?
He who is under an anathema looks yellow and his fingers are wrinkled.
He who looks white has been excommunicated by divine laws.
He who looks black has been excommunicated by a bishop.
Another part of the vrykolakas legend: if a vrykolakas knocked on the door and called your name, you must not answer. To answer meant that you would be dead within days (by sometimes unspecified means, although sitting on the chest of a sleeping victim was one method) and become one of the creatures yourself. However, unlike the postman, the vrykolakas would only call once, so it was a custom for Greeks to wait till they heard their name a second time before answering.
The island of Santorini, also known as Thera, was specifically known as a hotbed for vrykolakes. Simply Santorini's Greek Superstitions page claims that it was "known as the 'Island of the Vampires'", but no one seemed to know about them the one time I was privileged to visit the island. Both Lawson and the Superstitions page agree that Greeks on surrounding islands would bring the bodies of suspected vrykolakes to Santorini because experts in destroying the creatures resided there.
When I decided to write a story with a "Greek vampire", I set it on Santorini and introduced one such expert. Check it out on Amazon if you're interested.