Vurkolak

A vurkolak (also vǎrkolak or vǎlkolak) is an undead revenant or monster in Bulgarian folklore. According to the legends, when a person died in the wilderness, after 40 days, his swollen corpse or his blood turns into a vurkolak. In North-Western Bulgaria, the vurkolak is a wolf-like creature that devours the sun and the moon.

Vurkolak in "The Bleeding Moon"
The blood of murder victim Todor became a vurkolak, which plagued his native village of Gramada for a time. When the vurkolak attempted to devour the moon one night, the whole village produced as much noise as possible to drive it off. Finally, headman Symeon and his brother Rossen fired off their large guns. The noise frightened off the vurkolak.