William Turnbull (fl. 1448-1454) is important as a major figure in the government of Scotland and as founder of the University of Glasgow. He studied at St Andrews, Louvain (in modern Belgium) and Pavia (northern Italy). He became Keeper of the Privy Seal (1440 – 48) and Secretary to James II (c.1441-2). He was bishop-elect of Dunkeld when translated to Glasgow with the support of the Pope and King James who paid for the necessary papal bulls.
James II created the city, barony and Bishop's Forest of Glasgow, a regality for the bishop (1450) and forbade the men of Renfrew and Rutherglen from taking tolls within Glasgow's territory. Turnbull obtained from Pope Nicholas V the bull of foundation of the University (1451). The motives for this foundation seem to have been to uphold the Catholic faith and to promote the study of law. James took the university under his protection and granted members immunity from taxation. The Pope granted an indulgence to those visiting the cathedral during a four-month period in 1451, one third of the offerings going to the maintenance of the cathedral where Turnbull completed the upper chapterhouse.
Turnbull probably advised James about his marriage. He was involved in the overthrow of the Livingstones and the Earl of Douglas who was feared as a threat to royal authority, lending James money during the revolt of Douglas's supporters. He took part in diplomacy with France, England and Veere (Netherlands). He had permission to visit Rome in 1454, but probably died in Glasgow. He may have been buried at Cambuslang.