Cry of the Banshee (1970)

Monomaniacal witch hunter Lord Edward Whitman (Vincent Price) cruelly persecutes the peasants in his corner of Elizabethan England, manufacturing charges and meting out punishment without regard to justice. While trying to wipe out a coven of witches, he fails to take into account the possibility that real witches might have real power. He is unprepared when Oona (Elisabeth Bergner), the head of the coven, transforms a trusted member of Whitman's household into a vehicle of demonic vengeance.