Gilles de Montmorency-Laval, Baron de Rais (1404–1440) was the basis for the legendary Bluebeard; the most infamous serial murderer of the High Middle Ages.
An example of what happens when a sick mind is in a position where no one is able to tell him “no,” Gilles was vain and materialist. Eager to for fame, he achieved his goal as a hero of the Hundred Year Wars as a one-time compatriot of Joan of Arc, including the Siege of Orleans. When he retired from public life he grew to depravity when he returned to his estates in Brittany.
He is said to have murdered between 140-200 peasant children. His style was typical of most children murderers; he would dress them finely, feed them, get them drunk on wine; then, before long, he’d take them to an isolated location, sexually assault, torture, and kill them; mutilating their bodies afterwards. The victim’s parents would be turned away if they sought to question the Baron about the whereabouts of their children. His assistants were composed mostly of his one-time victims that he allowed to live and serve him, another trait expressed by contemporary child killers.
He was finally caught in 1440 when, after a dispute with the Archbishop of Nantes, he assaulted and kidnapped a cleric. The following investigation by the Archbishop and the Duke of Brittany revealed extent of this horrible tale. He was hung up and burned to death following his confession and trial. His victims-turned-assistants were done the same way, in their turn.
Jean Benedetti’s The Real Bluebeard: The Life of Gilles de Rais (1971) is still the standard biography for the Baron if you are curious to learn about this subject. I highly recommend it, though I do not believe it is currently in print.
Pictures (taken from the WikiCommons:
1) the Ruins of the Baron’s Chateau de Tiffauges.
2) an 18th century print of Gilles de Rais thought to be taken from a now lost contemporary portrait.
3) a 19th century depiction of Gilles committing his crimes at the behest of the devil
4) the blason of Gilles de Rais, Dore’s depiction of the Bluebeard fairy tale.
5 & 6) 16th Century depictions of his trial and execution.