Duke of Clarence was a substantive title created three times in the Peerage of England. The title Duke of Clarence and St Andrews has also been created in the Peerage of Great Britain, and Duke of Clarence and Avondale and Earl of Clarence in the Peerage of the United Kingdom. The titles have traditionally been awarded to junior members of the English and British royal family, and all are now extinct.

Lionel of Antwerp, Duke of Clarence,, was an English prince, Earl of Ulster jure uxoris from 1347, Duke of Clarence from 1362, Guardian of England in 1345-1346, Lord Lieutenant of Ireland in 1361-1366, Knight of the Garter from 1361, second surviving son of King Edward III of England and Philippa of Hainault. He was named after his birthplace, at Antwerp in the Duchy of Brabant.