William VIII, Marquess of Montferrat

William VIII Palaiologos (19 July 1420 – 27 February 1483) was the Marquess of Montferrat from 1464 until his death.

He was the third son of Marquess John Jacob, and inherited the Marquisate after the death of his elder brother John IV. He obtained by Emperor Frederick III the territories lost to Savoy from 1435. William served as condottiero for Francesco I Sforza of Milan and was later the tutor of the latter's son Galeazzo Maria. When the latter was assassinated, William acted as moderator in the Duchy of Milan.

William married firstly on 19 Jan 1465 Marie de Foix (d.1467); and secondly on 18 Jul 1469 Elizabetta Sforza (1456-1473); and finally on 6 Jan 1474 Bernarde de Brosse (d.17 Feb 1485).

Although William was married thrice, but all the times without legitimate son. He thenceforth had his daughters by his second marriage, Giovanna married to Ludovico I of Saluzzo and Blanche of Montferrat to Charles II of Savoy.

When he died in Casale Monferrato, he was succeeded by his brother Boniface.