William Fitzwilliam, 1st Earl of Southampton (c. 1450–1539), was an English nobleman and politician during the late medieval period. He served as a key figure in the court of King Henry VIII and held various important positions, including Lord High Admiral. His influence extended through his connections with the royal family and his role in the governance of England. Fitzwilliam was granted the title of Earl of Southampton in 1525, reflecting his status and contributions to the crown. He was also involved in military campaigns, including the Battle of Flodden in 1513, showcasing his commitment to the defense of England during a time of political turbulence.