This list of mythical creatures that begin with this letter and I am constantly gathering information from each continent, and is continually being updated.
Plakavac (Slavic)
Plakavac – recorded in Herzegovina, is a newborn strangled by its mother, which will rise from its grave at night as small vampire-like creature, return to its house and scream around it, but otherwise can't do any harm; Poroniec – a hostile and malicious demon from Slavic mythology.
It has different names depending on the country. In Serbia it's called Drekavac; it's named Plakavac by Herzegovina. The basic idea is that it's a supernatural manifestation of a dead infant or very young child.