Prince William of Gloucester was a grandson of King George V and paternal cousin of Queen Elizabeth II. At birth he was fourth in line to the throne; he was ninth in line at the time of his death.

This is a complete list of the children, grandchildren, great-grandchildren and great-great-grandchildren of King George V, the founder of the House of Windsor, and his queen Mary of Teck. The list includes deceased members, members who have become Catholic, royal and non-royal, legitimate and illegitimate members openly acknowledged by their parents.