William Guthrie (1620 – October 10, 1665) was a Scottish preacher, Covenanter, and author whose brief but impactful ministry in Fenwick, Ayrshire, and his book The Christian’s Great Interest left a lasting legacy in Presbyterian circles. Born at Pitforthy, Forfarshire, to James Guthrie, laird of Pitforthy, and a daughter of Lyon of Easter-Ogle, he was the eldest of eight children, four of whom entered the ministry. Educated at the University of St Andrews under his cousin James Guthrie—a future martyr—he graduated with an M.A. in 1638, then studied divinity under Samuel Rutherford. To focus on ministry, he relinquished his inheritance of Pitforthy to a brother. Licensed by the Presbytery of St Andrews in August 1642, he tutored James, son of John Campbell, Earl of Loudoun, before his ordination as Fenwick’s first minister on November 7, 1644, overcoming opposition from the royalist patron, Lord Boyd. Guthrie’s preaching career at Fenwick was marked by fervent Gospel proclamation and pastoral care, despite fragile health prone to melancholy. Known for creative evangelism—once bribing a hunter with half-a-crown to attend church—he preached with tender urgency, drawing from sports like curling to connect with his flock. His masterpiece, The Christian’s Great Interest (1658), based on Isaiah 55 sermons, countered a pirated 1657 edition and offered assurance to believers, translated into French, German, Dutch, Gaelic, and an Eastern language funded by Robert Boyle. A Covenanter, he sided with the Protesters during Scotland’s church schism, serving as Moderator of the Glasgow and Ayr Synod in 1654. Deposed in 1664 for non-conformity after the Restoration, he preached his last Fenwick sermon that year.