William of Montferrat

William of Montferrat is the name of:
 * William I of Montferrat (d. before 933)
 * William II of Montferrat (died probably around 961)
 * William III of Montferrat (991 – bef.1042), son of Otho I
 * William IV of Montferrat (c.1084–c.1100)
 * William V of Montferrat (c.1136–1191)
 * William of Montferrat, Count of Jaffa and Ascalon (c. 1140–1177), also called William Longsword (early 1140s–1177)
 * William VI of Montferrat, (1207–1225)
 * William of Montferrat (monk), 13th century
 * William VII of Montferrat (c.1255–1292), titular king of Thessalonica
 * William VIII of Montferrat (1464–1483)
 * William IX of Montferrat (1494–1518), see Casale Monferrato
 * William X of Montferrat, 1st duke of Montferrat, Duke of Mantua