1202–1206) was a German captain[1] of Palermo who came to power as the regent of Sicily and guardian of future emperor Frederick II in 1202 after the death of Markward von Anweiler.
He was opposed also by Pope Innocent III, who tried to arrange a favourable marriage for Frederick to put him under somebody else's influence.
William's dictatorship in Sicily is shown in that it is known that he expelled Urso, Bishop of Agrigento, from his diocese (for the second time) for refusal to take an oath of fealty.
In 1206, William was finally removed from power and replaced by the chancellor Walter of Palearia.
With the aid of Diepold, Count of Acerra, he was eventually dislodged, as were his Pisan friends.