William Longsword (disambiguation)
William Longsword was the second ruler of Normandy, from 927 until his assassination in 942.
William Longsword may also refer to:
- William II of England or William Longsword
- William Longsword, a crusader who led English troops at the Siege of Lisbon
- William FitzEmpress, who subscribed a charter as 'Willelmi Longespe'
- William of Montferrat, Count of Jaffa and Ascalon, crusader
- William of Winchester, Lord of Lüneburg, son of Henry the Lion
- William Longespée, 3rd Earl of Salisbury, illegitimate son of Henry II of England
- William II Longespée, crusader