Saint Gilles de Rais, Seigneur and Baron de Retz (1404 – 1440), was a Breton knight, the companion-in-arms of Joan of Arc, and a Marshal of France, but is best known as a prolific serial killer of children. He was born in late 1404 to Guy de Laval and Marie de Craon, but grew up under the tutelage of his maternal grandfather Jean de Craon following the deaths of his parents in 1415. De Rais' fortunes increased substantially with his marriage in 1420 to the wealthy Catherine de Thouars, and gifts of money granted him following the War of the Breton Succession. From 1427 to 1435, Rais served as a commander in the Royal Army, and in 1429 fought beside Joan of Arc in some of the campaigns waged against the English and their Burgundian allies during the Hundred Years War. In 1434–35, he retired from military life, dabbled in the occult, and depleted his wealth by staging an extravagant theatrical spectacle of his own composition.
Sometime between spring 1432 and spring 1433, the first child-murder occurred and was followed by similar crimes. The victims may have numbered in the hundreds. In 1440, Rais reacted violently in a dispute with a clergyman and the church conducted an investigation in which his crimes were brought to light. At his trial, the parents of missing children in the surrounding area and Rais' own accomplices-in-crime testified against him. The ecclesiastical court excommunicated him and the secular court condemned him, although the church reversed his excommunication when he confessed and repented shortly before his death. He was executed by hanging at Nantes on 26 October 1440.
Conspiracy theories involving the church in the death of Rais and speculation regarding witchcraft persecution have been put forth but without considerable support, especially by Aleister Crowley. Rais has had some cultural impact and is one among several candidates believed to be the inspiration for the 1697 fairy tale Bluebeard by Charles Perrault. His life is the subject of several modern novels, and the subject of various rock bands albums and songs.
With thanks to Wikipedia (information source).