Louise Henriette (20 June 1726 – 9 February 1759), Mademoiselle de Conti at birth, was a French princess, who, by marriage, became Duchess of Chartres (1743–1752), then Duchess of Orléans (1752–1759) upon the death of her father-in-law. On 4 February 1752, her husband became the head of the House of Orléans, and the First Prince of the Blood (Premier prince du sang), the most important personage after the immediate members of the royal family. The new Duke of Orléans and his wife were then addressed as Monsieur le Prince and Madame la Princesse. Louise Henriette de Bourbon, Duchess of Orléans, was a grandmother of the French monarch Louis-Philippe King of the French, "the Citizen King". Her descendants include the present-day pretenders to the throne of France and Italy and the kings of Spain and Belgium.