The Eretica is a Greek vampire, although some claim it a Russian vampire.
When looking at Greek mythology, the Eretica is in association with Hecate. They are described as demons that can take human form.
When looking at Russian folklore, the Eretica myths stem from the belief that heretics were punished by members of the undead after death. Heretics that used magic, were most likely to turn into a vampire creature after death. Sorcerers and witches, for example, would turn into vampires once they died. A person could also turn into an Eretica if they do not confess their sins before death. The fear of being a bad Christian drove the Russian believe in Ereticas.
The Eretica was often thought to be a woman who sold her soul to the devil while she was alive, and when she died, she became an old woman in rags. At night and only during spring and late fall, she would gather others like her where they would have a sabbot.
In order to destroy the vampire creature, the body would need to be burned or staked with a stake made of aspen.