When it comes to 14th-century French nobility, there are few characters more illustrious (and more terrifying) than Gilles de Rais. Rais began his life as a darling of the French military, and he even fought alongside Joan of Arc during the Hundred Years' War.
However, later in his life, it was revealed that Rais was always up to no good.
Stranger still was the nobleman's supposed involvement in the occult.
After severely depleting his family's fortune, Rais dabbled in the occult. He hoped to broker with demons as a way to get more wealth. For several months, one of his friends attempted to summon one; however, after the demon failed to appear, the friends concluded that the demon needed a human sacrifice. That's when Rais started killing.