Barclay, William was born in Aberdeen, Scotland, about 1545, was a Roman Catholic, and a favorite of Mary Queen of Scots. After her fall he went to France, studied law, and was made professor of that branch at the new University of Pont- A-Mousson. Finding that the Jesuits were likely to draw his son John into their ranks, SEE BARCLAY, JOHN, he left the University, returned to England, and was offered a professorship of civil law at one of the universities if he would conform to the Anglican Church. This, however, he refused to do, and returned to France, where he was made professor at Angers, and died in 1605 (or 1609). He wrote (besides other works on law, etc.) De Potestate Papae, an et quatenus in Reges et Principes seculares Jus et Impereium habeat (London, 1609, 8vo; Pont-h-Mousson, 1610, 8vo; transl. into French, Pont-a-Mousson, 1611; Cologne, 1688, 8vo). In this work he vindicates the independent rights of princes against the usurpations of the pope. — Bayle, Dictionary, s.v.; Hoefer, Nouv. Biog. Generale, 3, 471.