William Guthrie (1620–1665) was a Scottish Covenanter minister and author. He was the first minister of Fenwick parish church in Ayrshire, Scotland. He is known primarily for his book on assurance, The Christian's Great Interest. William Guthrie, born 1620, was the eldest son of James Guthrie of Pitforthie, Forfarshire, by a daughter of Lyon of Easter-Ogle, in Tanadice parish. He be came an apt scholar, and on 5 June 1638 he graduated M.A. at the University of St Andrews, where his studies had been directed by his cousin, James Guthrie, then a regent in philosophy. He studied divinity under Samuel Rutherford. To free himself from what he considered purely worldly affairs, he made over Pitforthie to one of his brothers. He was licensed by the Presbtery of St Andrews in August 1642, and became tutor to the eldest son of John Campbell, first Earl of Loudoun, the Lord High Chancellor of Scotland. Some persons from Fenwick having heard him preach at a Fast-day service in Galston Kirk, they desired him to be called as the first minister of their newly created parish. That was done, and he was ordained 7 November 1644. Soon afterwards the General Assembly appointed him an army chaplain, and he was present at the engagement which took place at Mauchline Moor in June 1648. He also witnessed the covenanting defeat at Dunbar on 3 September 1650. He joined the Protesters in 1651. On 8 August 1654 he was appointed by the English Council on a committee for supervising admissions to the ministry within the bounds of his own Synod. Refusing to submit to Episcopacy, he was deprived 24 July 1664. He went to Pitforthie, which had again come into his hands through the death of his brother, and following a period of ill-health, he died in the manse of his brother-in-law, Laurence Skinner, minister of Brechin, 10 October 1665, and was buried in the Cathedral there. Character Hew Scott says he was a man of ready wit, who moved freely amongst his people, lived simply, and spent a great part of his leisure in such sports as fishing and fowling. When he preached his church was crowded, and his pastoral work was performed with undiminished fervour and success throughout all his ministry. He refused calls to Renfrew, Linlithgow, Stirling, Glasgow, and Edinburgh. Dr John Owen describes him as "one of the greatest divines that ever wrote."