Etienne Guibourg

The Abbé Étienne Guibourg (c. 1610 – January 1686) was a French Roman Catholic abbé and occultist who was involved in the affaire des poisons, during the reign of Louis XIV. He has been variously described as a "defrocked" or "renegade" priest and is said to have also had a good knowledge of chemistry. He is best known for performing a series of Black Mass rituals with Catherine Monvoisin for Madame de Montespan.

Guibourg claimed to be the illegitimate son of Henri de Montmorency.

He was the sacristan of the Saint-Marcel church at Saint-Denis which was later destroyed during the French Revolution but described as being "the most beautiful of the parish churches of the town of Saint-Denis". He was formerly the chaplain to the Comte de Montgomery.

Despite his position, he is said to have kept a long-term mistress, Jeanne Chanfrain, with whom he had several children.

According to later accounts, confessions and trials, Guibourg performed a series of Black Masses with Catherine Monvoisin (known as La Voisin). The most famous of these were performed for Madame de Montespan around 1672-3. Montague Summers gives an account of one such ritual:

A long black velvet pall was spread over the altar, and upon this the royal mistress laid herself in a state of perfect nudity. Six black candles were lit, the celebrant robed himself in a chasuble embroidered with esoteric characters wrought in silver, the gold paten and chalice were placed upon the naked belly of the living altar [...] All was silent save for the low monotonous murmur of the blasphemous liturgy [...] An assistant crept forward bearing an infant in her arms. The child was held over the altar, a sharp gash across the neck, a stifled cry, and warm drops fell into the chalice and streamed upon the white figure beneath. The corpse was handed to la Voisin, who flung it callously into an oven fashioned for that purpose which glowed white-hot in its fierceness.

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