William the Old was a 12th-century prelate who became one of the most famous bishops of Orkney. Although his origins are obscure in detail, William was said to have been a "clerk of Paris", which Barbara E. Crawford interprets as meaning that he had received his theological training in northern France. Saga tradition had it that William had been bishop for 66 years when he died in 1168, meaning that his accession to the bishopric would have been around 1102. There is no contemporary evidence of his episcopate until a letter of Pope Honorius II in 1128, which even then does not name William specifically, but rather only mentions a bishop holding office at the same time as Radulf Novell. He was however definitively in charge by December 1135 during the earldom of Earl Paul Haakonsson.