With red hair being rare, a child born to non red headed parents was often assumed to be the child of an affair. Thus was treated badly, usually in the form of beatings.
A red headed strangler is a scary guy with red clown hair on the sides yet bald on top. A red headed strangler has large hands and hangs out at laundry mats. Often seen with a creepy flashlight on a hat and lots of safety pins and keys.