We all learned about the Witch Trials in history class, but did you know that Werewolf Trials were a thing too? The cannibal Peter Stumpp, who was nicknamed the Werewolf Killer, was the catalyst for the hysteria that took over Europe. This caused several townies to fear that they were going to be eaten by a werewolf. He is known to be one of the most gruesome serial killers of all time.