The Black Nun of Moret, Louise Marie-Thérèse (1664–1732) was a Benedictine nun in the abbey of Moret-sur-Loing. She was called the "Mauresse de Moret", and a portrait of her exists in the Bibliothèque Sainte Geneviève in Paris. The research done by the Société de l'histoire de Paris et d'Ile-de-France, published in 1924 by Honoré Champion éditions, concluded that this pastel portrait was painted around 1680 by the same hand which painted the series of twenty-two pastel portraits of Kings of France, from Louis IX to Louis XIV...Text and image from Wikipedia, via Miss Folly.
Shortly after the death of the French Queen Maria Theresa of Spain in 1683, wife of Louis XIV, courtiers pointed out this woman as the black daughter the Queen allegedly once gave birth to.
La Grande Mademoiselle tells that the child could be of the black page Nabo, of whom the Queen was very fond. The adultery thesis is not considered likely, as the Queen was a very pious woman, and there is no knowledge of even the slightest mistake of hers. It would be very difficult in Versailles to have a liaison and even to give birth in secret. Every Royal birth happened in public, in the Queen's bedchambers, with all courtiers present as witnesses. The little princess Marie-Anne was born (16 November 1664) with a dark skin caused by cyanosis, and died shortly after birth (26 December 1664). Some say that the baby remained black, and had been changed with a dead girl, to avoid scandal. According to Madame, wife of Louis XIV's brother, her husband said that the child was not black at all but very ugly. In any case, although the story about the black daughter of Maria Theresa is unconfirmed, it was still persistent and believed by many.