William Dell (c. 1607–1669) was an English clergyman, Master of Gonville and Caius College, Cambridge from 1649 to 1660, and prominent radical Parliamentarian.
Dell was born at Bedfordshire, England, and was an undergraduate at Emmanuel College, Cambridge, taking an M.A. in 1631. He became a chaplain in the New Model Army, which brought radical ministry with it.
Dell's 1646 sermon to the lower house in Parliament, following a controversial one to the House of Lords, was too extreme, and the House of Commons reprimanded him; it attacked the Westminster Assembly, spoke up for the poor, and told the politicians to keep out of religious reform. Nonetheless his appointment at Caius was at the behest of the Rump Parliament. Thomas Harrison's proposal to have him preach again, in 1653, was defeated.
He criticized those on the Parliamentarian side who had done well out of the war. According to Christopher Hill
He backed the Quaker John Crook as MP in 1653/4, and the regicide John Okey. He was a supporter of Oliver Cromwell. In 1657, however, he with Okey campaigned against the proposal to make Cromwell king.
He was a friend and supporter of John Bunyan, whom he invited to preach in his parish church. He was an opponent of the Ranters; but also of enforced uniformity of worship, citing Martin Luther against it He was attacked as a libertine, and thought to tend to antinomianism. According to Christopher Hill
He preached the doctrine of free grace, and subscribed to the idea of continuous revelation; and is included in those considered preachers of the Everlasting Gospel.