Strzyga
Strzyga (rarely also in masculine form as strzyg or strzygoń) is a demon from Slavic mythology.
Origin
According to Aleksander Brückner, the word is derived from Strix, Latin for owl and probably the origin of the term Strigoi, a troubled soul of the dead rising from the grave in Romanian mythology. It is unclear how the word strzyga was adapted by the Polish people.
Beliefs
A strzyga (Polish pronunciation: [ˈstʂɨɡa]) is a female demon somewhat similar to vampire in Slavic (and especially Polish) folklore. People who were born with two hearts and two souls and two sets of teeth (the second one barely visible) were believed to be strzygas. Furthermore, a newborn child with already developed teeth was also believed to be one. When a person was identified as a strzyga he was chased away from human dwelling places. Such strzygas usually died at a young age, but, according to belief, only one of their two souls would pass to the afterlife; the other soul was believed to cause the deceased strzyga to come back to life and prey upon other living beings. These undead strzyga were believed to fly at night in a form of an owl and attack night-time travelers and people who had wandered off into the woods at night, sucking out their blood and eating their insides. Strzyga were also believed to be satisfied with animal blood, for a short period of time.
When a person believed to be a strzyga died, decapitating the corpse and burying the head separate from the rest of the body was believed to prevent the strzyga from rising from the dead; burying the body face down with a sickle around its head was believed to work as well.
According to the other sources strzygas were believed not to harm people but to herald someone's imminent death. In this they resemble Banshees.