Princess Isabelle of Orléans (Isabelle Marie Laure Mercédès Ferdinande; 7 May 1878 – 21 April 1961) was a member of the French Orleanist royal family and by marriage Duchess of Guise.

She was born at Eu, France, the daughter of Prince Philippe, Count of Paris and Infanta Maria Isabel of Spain.

She married, at Twickenham, on 30 October 1899, her first cousin Prince Jean, Duke of Guise (1874–1940). Jean was the son of prince Robert, Duke of Chartres (1840–1910) and Françoise d'Orléans (1844–1925).

Upon the death of his cousin Philippe of Orléans, Duke of Orléans, claimant to the throne of France as "Philip VIII", the Duke of 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:

Princess Isabelle died in Larache, Morocco.

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