last legitimate descendant of the deposed (1688) Stuart monarch James II of Great Britain. To the Jacobites—supporters of Stuart claims to the British throne—he was known as King Henry IX of Great Britain for the last 19 years of his life.

Shortly after his birth, Stuart was named duke of York by his father, the exiled Stuart claimant James Edward, the Old Pretender, son of James II. Stuart raised forces in France to help his elder brother, Charles Edward, the Young Pretender, during the unsuccessful Forty-five Rebellion (Jacobite rebellion of 1745–46), but the uprising was crushed before Stuart's troops could be deployed. In 1747 the pious, mild-mannered duke was created cardinal of York by Pope Benedict XIV. He was consecrated archbishop of Corinth in 1758 and was later (1761–1803) bishop of Frascati, in Italy.

Upon the death of the Young Pretender in 1788, Stuart proclaimed himself king as Henry IX. He lost his property during the Napoleonic invasion of Italy, and after 1800 he survived on a yearly pension granted him by King George III of England.