Ордерик Виталий
William of Montreuil () († aft. 1068), was an Italo-Norman freebooter of the mid-eleventh century who was briefly Duke of Gaeta. He was described by Amatus of Monte Cassino as "an exceptional knight, small in stature, who was very robust, strong, valiant" and by Orderic Vitalis as 'the good Norman' ().