The strzyga is a horrifying demon and one of the most famous ones in Slavic mythology, especially due to its connection to vampires and its prevalence in the popular Witcher series (which has roots in both Polish and Celtic myths). Pictured as a person (usually female, sorry ladies) born with two sets of teeth, two hearts, and two souls, they are often driven out of villages for being evil spirits at a young age. And when they die in the wilds, one of their souls passes to the next life, but the other remains as fully demonic.
At first, even the fully strzyga person may appear normal with perhaps slightly more blue-ish skin. Soon, though, they begin to develop owl-like features such as feathered wings, long and pointed ears, and vicious claws. In addition to their two jagged sets of teeth, these characteristics make them vicious predators—predators that hunt humans.
Since the strzyga is fully a demon now, they must rely on the life force of others to survive. They sleep in graves during the day and emerge at night, and though they can initially survive on animal blood for some time, they will soon develop the need to ravage humans. It was well known that they would especially target those who had wronged them in their “first” life, sucking their blood before eating their insides as well.
Among the strzyga’s tactics were to disguise themselves as a barn owl (because basically, everything in Slavic mythology is a shape-shifter) before retaking their true form and attacking. This is probably one of the major reasons that owls aren’t revered in Poland as much as in other areas. Recommendations for avoiding strzyga at night include walking in the middle of roads, avoiding heavy brush, and never going near cemeteries.
Summarising: Striga is dangerous, bloodthirsty and never forgives the one who wronged her. Tell me later if this is a fit nickname for our incorrigible Ina.
Description is taken from: https://brendan-noble.com/the-strzyga-striga-in-polish-mythology/)