Duke of Clarence and St Andrews was a title created in 1789 in the Peerage of Great Britain for Prince William Henry (later King William IV). He was also created Earl of Munster in the Peerage of Ireland at the same time.
While there had been several creations of Dukes of Clarence (and there was later a Duke of Clarence and Avondale), the only creation of a Duke of Clarence and St Andrews was for Prince William, third son of King George III. When William succeeded his elder brother George IV to the throne in 1830, the dukedom merged in the crown. The title refers to ancient castle and honour of Clare, Suffolk; and the Scottish city of St Andrews.
| Prince William Henry<br/>House of Hanover<br/>1789âÂÂ1830<br/> | | 21 August 1765<br/>Buckingham House, London<br/>son of George III and Charlotte of Mecklenburg-Strelitz | Adelaide of Saxe-Meiningen<br/>11 July 1818 | 20 June 1837<br>Windsor Castle, Windsor<br>aged 71 |- | colspan=5|Prince William Henry ascended as William IV in 1830 upon his brother's death; and his hereditary titles merged in the Crown. As William had no male issue, the title would have gone extinct in any case, even if he had not become king. |-