"The Bleeding Moon" is a short horror story by Harry Turtledove. It first appeared in the collection Orphans of the Night, edited by Josepha Sherman, Walker 1995. It has not been reprinted.
The setting is the small Bulgarian village of Gramada, c.a. 1546 CE, a century and a half after the Turks conquered the country. Three cousins, Petko, Todor and Georgi are hunting in the woods when Todor is murdered by men from the rival village of Kula. Todor's death gives birth to a vurkolak, a vampire-like shape-shifting monster. The vurkolak haunts the village, killing sheep and attempting to lure villagers to their deaths. After weeks of dread, the vurkolak attempts to devour the moon, forcing the villagers to act.