William III
William III or William the Third may refer to:
Kings
- William III of Sicily
- William III of England and Ireland or William III of Orange or William II of Scotland
- William III of the Netherlands and Luxembourg
Nobles
- William III, Duke of Aquitaine
- William II, Count of Provence, also numbered William III of Provence,
- William III, Count of Toulouse, also styled William III of Provence
- William III of Provence
- William III of Weimar
- William III, Marquess of Montferrat
- William III, Lord of Montpellier
- William V, Count of Angoulême, also known as William Taillefer III
- William III, Count of Burgundy
- William III of Forcalquier
- William III of Mâcon
- William III, Count of Nevers
- William III, Count of Ponthieu
- William III, Count of Jülich
- William II, Count of Flanders, also styled William III of Dampierre
- William de Cantilupe
- William III of Baux
- William III Giudice of Cagliari
- William III of Geneva
- William I, Count of Hainaut or William III of Holland
- William III, Earl of Ross, known as Uillearn, 5th Earl of Ross
- William I, Duke of Bavaria or William III of Hainaut
- William III, Duke of Bavaria
- William III of Isenburg-Wied
- William III, Princely count of Henneberg-Schleusingen
- William III, Landgrave of Thuringia
- William III, Landgrave of Hesse
Horses
- William the Third