William of the United Kingdom most commonly refers to:
- William IV of the United Kingdom (1765–1837; r. 1830–1837), known as Prince William, Duke of Clarence and St Andrews prior to ascension
- William, Prince of Wales (born 1982), current heir apparent to British throne as eldest son of Charles III, also known as Duke of Rothesay in Scotland
William of the United Kingdom or William of Great Britain may also refer to:
- Prince William, Duke of Cumberland (1721–1765), third and youngest son of George II
- Prince William Henry, Duke of Gloucester and Edinburgh (1743–1805), grandson of George II and brother of George III
- Prince William Frederick, Duke of Gloucester and Edinburgh (1776–1834), son-in-law of George III
- Prince William of Gloucester (1941–1972), grandson of George V
See also
edit- List of British monarchs
- List of English monarchs
- Prince William (disambiguation)#Royal princes, lists princes outside of British Isles named William
- William of England (disambiguation), lists kings named William in one predecessor state of United Kingdom prior to 1707
- William the Lion (c. 1142–1214; r. 1165–1214), also known as William I, King of Scots, reign was second longest in history of Kingdom of Scotland (another predecessor state of United Kingdom prior to 1707)