Prince Henry, Duke of Gloucester, KG, KT, KP, GCB, GCMG, GCVO, PC (Henry William Frederick Albert; 31 March 1900 – 10 June 1974) was a soldier and third son of King George V and Queen Mary.

Under the terms of the Regency Act 1937, the Duke would have been named regent for his niece, Princess Elizabeth (later Queen Elizabeth II), if his brother, King George VI, had died before Elizabeth reached her 18th birthday; he was also eligible to serve as a Counsellor of State from 1937 to 1974 (his death), if the monarch were incapacitated or absent from the country.

The Duke served as a soldier for most of his life. He was also the 11th Governor-General of Australia, from 1945 to 1947. At his death in 1974, he was the last surviving knight of the Order of St. Patrick, as well as the last surviving child of King George V and Queen Mary.

Prince Henry was born on 31 March 1900, at York Cottage, on the Sandringham Estate. His father was the Duke of York (later King George V), the eldest surviving son of the Prince of Wales, (later King Edward VII). His mother was Mary of Teck, the only daughter of Prince Francis, Duke of Teck and Princess Mary Adelaide of Cambridge. At the time of his birth, he was fifth in the line of succession to the throne, behind his grandfather, father and two elder brothers.

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