The Strix was a demon from Hell, created by Satan to engulf the souls of sinners and send them to Hell.
In the late 20th century, Strix escaped from hell and became a physical form on earth, possessing the souls of people all over Maine and transforming them into black birds. Without souls, the humans were rendered zombies. Eventually, Strix hid in Collinwood and terrorized the Collins family and the towns people, eventually devouring Barnabas Collins and destroying his body. When Quentin Collins returned to Collinwood to claim his home, he learned that the house was inhabited by Strix and that the Collins family had fled. So Quentin raised Angelique Collins from the dead to aid him. Together, Quentin and Angelique battled Strix, and eventually defeated it.