His Royal Highness Prince William Henry Andrew Frederick of Gloucester (December 18, 1941-August 28, 1972) was the elder son of the late Prince Henry, Duke of Gloucester and Princess Alice, Duchess of Gloucester.

Prince William was born at Barnet, Hertfordshire. He spent his early childhood at Barnwell Manor in Northhamptonshire and in Australia, where his father served as governor general from 1945 to 1947. He received his education at Wellesley House Prepratory School, Broadstairs, Kent, and at Eton College. After leaving Eton in 1960, he went to Magdalene College, Cambridge to read history. After graduating in 1963, he spent a post-baccalaureate year at Stanford University studying political science, American history, and business. Upon returning to Great Britain, he took a position with Lazards, a merchant bank.

Prince William was the second member of the British Royal Family to work in the civil service or the diplomatic service. (The first was his late uncle, Prince George, Duke of Kent in the 1920s). He joined the Foreign and Commonwealth Office in 1965 and was posted to Lagos as the third secretary to the British High Commission. In 1968, he transferred to Tokyo to accept the post of second secretary (commercial) in the British Embassy. In 1970, the Duke of Gloucester's health began to fail. Prince William resigned from the diplomatic service and returned to Britain. For the next two years, he managed Barnwell Manor and began to carry out public duties as a member of the royal family.

A certified pilot, he owned several aircraft and competed in several air shows. He died when the plane he was piloting crashed at Halfpenny Green, near Wolverhampton. He was buried at Frogmore Royal Burial Ground.

Prince William was the heir apparent of his father's peerages, Duke of Gloucester, Earl of Ulster, and Baron Culloden. Upon his death, his younger brother Prince Richard of Gloucester became heir and succeeded to these peerages in 1974.