Catherine Sheffield, Duchess of Buckingham and Normanby

Catherine Sheffield, Duchess of Buckingham and Normanby (also spelled Katherine; c. 1681 – 13 March 1743), known as Lady Catherine Darnley until 1699 and as Catherine Annesley, Countess of Anglesey, from 1699 to 1706, was an English Jacobite noblewoman, and the acknowledged illegitimate daughter of James Stuart, Duke of York, later King James II, by his mistress Catherine Sedley, Countess of Dorchester. By royal warrant she was granted the precedence of a duke’s daughter, and through her father was half-sister to Queen Mary II, Queen Anne and James Francis Edward Stuart.

She married firstly James Annesley, 3rd Earl of Anglesey, but shortly after she obtained a divorce on account of his cruelty, and afterwards married John Sheffield, 1st Duke of Buckingham and Normanby. She became a prominent Tory and Jacobite figure at the court of Queen Anne and a consistent supporter of the Stuart succession. Commonly nicknamed "Princess Buckingham", she resided at Buckingham House (on the site of the present Buckingham Palace), and was noted for her haughty sense of rank, ostentatious style and forceful temperament, and was frequently compared with her contemporary and rival Sarah, Duchess of Marlborough. Her London drawing room was regarded as a principal gathering place for Tory politicians and Jacobite sympathisers in the early eighteenth century, often contrasted with the Whig circle at Marlborough House, and she actively promoted the claims of her half-brother James Francis Edward Stuart. Through her only surviving child, Lady Catherine Annesley, she is ancestress of the Phipps family, later Marquesses of Normanby. She died in 1743 and was buried in the Henry VII Chapel of Westminster Abbey.