Louise Marie Adélaïde de Bourbon-Penthièvre, Duchess of Orléans (13 March 1753 – 23 June 1821), was the daughter of Louis Jean Marie de Bourbon, Duke of Penthièvre and Princess Maria Teresa d'Este. At the death of her brother, Louis Alexandre de Bourbon, "prince de Lamballe", she became the wealthiest heiress in France. She married the future "Philippe Égalité", and was the mother of France's last king, Louis Philippe I. She was a princess of the blood by her marriage.