William Cavendish, 1st Duke of Newcastle (d. 1676)
William Cavendish, 1st Duke of Newcastle upon Tyne, KG, KB, PC (c. 16 December 1593 – 25 December 1676) was an English courtier and supporter of the arts. He was a renowned horse breeder, as well as being patron of the playwright Ben Jonson, and the intellectual group known as the Welbeck Circle.

Despite spending the then enormous sum of £15,000 entertaining Charles I in 1634, he failed to gain a significant political post. In the early stages of the First English Civil War, he was appointed Royalist Captain-General in Northern England; he financed much of the war effort himself, later claiming this totalled in excess of £1,000,000. After the defeat at Marston Moor in July 1644, a battle fought against his advice, he went into exile in Europe.

He returned to England after the 1660 Restoration; although created Duke of Newcastle in 1665, he remained on the fringes of the court, and became critical of Charles II. He died in 1676, and was buried in Westminster Abbey.