William III

William III or William the Third may refer to:

Kings

 * William III of Sicily (c. 1186)
 * 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 (c. 970–1037)
 * William III of Provence (died after 1037)
 * William III of Weimar (died 1039)
 * William III, Marquess of Montferrat (c. 970–1042)
 * 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 (c. 1110–1127)
 * William III of Forcalquier (died 1129)
 * William III of Mâcon (1088–1156)
 * William III, Count of Nevers (c. 1107–1161)
 * William III, Count of Ponthieu (c. 1093–1172)
 * William III, Count of Jülich ((r. 1207 – 1219))
 * 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 Giudice of Cagliari ((r. 1256 – 1258))
 * William III of Geneva (1280-1320)
 * William I, Count of Hainaut or William III of Holland (c. 1286–1337)
 * William III, Earl of Ross, known as Uillearn, 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 ((r. 1413 – 1462))
 * William III, Princely count of Henneberg-Schleusingen (1434–1480)
 * William III, Landgrave of Thuringia (1425–1482)
 * William III, Landgrave of Hesse (1471–1500)

Horses

 * William the Third (horse)