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 (1650–1702)
• William III of the Netherlands and Luxembourg (1817–1890)

Nobles

• William III, Duke of Aquitaine (913–963)
• William II, Count of Provence, also numbered William III of Provence, (late 980s–1018)
• William III, Count of Toulouse, also styled William III of Provence (–1037)
• William III of Provence (died after 1037)
• William III of Weimar (died 1039)
• William III, Marquess of Montferrat (–1042)
• William III, Lord of Montpellier (died 1058)
• William V, Count of Angoulême, also known as William Taillefer III (1084–1118/20)
• William III, Count of Burgundy (–1127)
• William III of Forcalquier (died 1129)
• William III of Mâcon (1088–1156)
• William III, Count of Nevers (–1161)
• William III, Count of Ponthieu (–1172)
• William III, Count of Jülich ()
• William II, Count of Flanders, also styled William III of Dampierre (1224–1251)
• William de Cantilupe (died 1254)
• William III of Baux (died 1257)
• William III of Cagliari ()
• William III of Geneva (1280-1320)
• William I, Count of Hainaut or William III of Holland (–1337)
• William III, Earl of Ross, known as ', 5th Earl of Ross (died 1372)
• William I, Duke of Bavaria or William III of Hainaut (1330–1389)
• William III, Duke of Bavaria (1375–1435)
• William III of Isenburg-Wied ()
• William III, Princely count of Henneberg-Schleusingen (1434–1480)
• William III, Landgrave of Thuringia (1425–1482)
• William III, Landgrave of Hesse (1471–1500)