The next entry in my bestiary is the drekavac.
Drekavacs are from Slavic folklore and come in many forms. The main things they are known for are that they scream and howl and are usually invisible. Said to be created when an unbaptized child dies and rises from the grave, drekavacs take many forms, depending on Slavic area they're in. Sometimes they're a human spirit, sometimes they're a dog or a cat with human features. In some areas they're described as a spindly creature with a long neck and overlarge head. In human form, hearing or seeing one predicts the death of a human. When in animal form, they predict cattle illness.