Jean Pierre Clément Marie d'Orléans, Duc de Guise (September 4,1874 - August 25,1940) was the son of Robert, Duke of Chartres (1840-1910), grandson of Prince Ferdinand-Philippe and great-grandson of Louis Philippe I, King of the French. His mother was Marie-Francoise d'Orléans, daughter of François d'Orléans, prince de Joinville and Princess Francisca of Brazil.
Upon the death of his cousin Philip VIII, Count of Paris, claimant to the throne of France as Philip VIII, the Duc de Guise became, at least for his Orleanist supporters, titular king of France as Jean III. The title was disputed by members of the Spanish Anjou branch of the family, descended from Louis XIV.
They had four children:
Jean III died in Larache, Morocco, in 1940.