Samuel Clarke (11 October 1675 – 17 May 1729) was an English philosopher and Anglican cleric. He is considered the major British figure in philosophy between John Locke and George Berkeley. Clarke's altered, Nontrinitarian revision of the 1662 Book of Common Prayer continues to influence worship among modern Unitarians.

Clarke was born in Norwich, the son of Edward Clarke, an alderman of Norwich and Member of Parliament, and brother of John Clarke. He was educated at Norwich School and Gonville and Caius College, Cambridge. His tutor at Caius was John Ellis, a personal friend of Isaac Newton, but who in natural philosophy taught in line with the Cartesianism that prevailed in the university.

Clarke, however, came to adopt the new physical system of Newton; he used the vehicle of an annotated translation of a work on physics in the Cartesian tradition to comment on the superiority of the Newtonian system. This textbook was published in 1697, and in the same year Clarke met the Newtonian William Whiston. It was a chance encounter in Norwich, but Whiston was then chaplain to John Moore, bishop of Norwich. Having taken holy orders, Clarke became chaplain to Moore in Whiston's place, and was presented by Moore to the rectory of Drayton, Norfolk.

In 1706, through the influence of Moore, Clarke obtained the rectory of St Benet Paul's Wharf, London. Soon afterwards Queen Anne appointed him one of her chaplains in ordinary, and in 1709 presented him to the rectory of St James's, Westminster. His church brought Clarke into personal contact with Newton.

Clarke was Boyle lecturer for two years, and produced two books. The Newtonian theologians used the Boyle Lectures to attack opponents (Thomas Hobbes and Baruch Spinoza, deists and freethinkers in particular). Clarke's lectures set the agenda for further debates. He dealt in 1704 with the Being and Attributes of God, an example of a physico-theological system; and in 1705 with the Evidences of Natural and Revealed Religion. These books were later published together.

Clarke's reputation rested largely on his effort to demonstrate the existence of God, and his theory of the foundation of rectitude. The former is not a purely a priori argument, and it was not presented as such. The intelligence, for example, of the self-existence and original cause of all things is, he says, "not easily proved a priori," but "demonstrably proved a posteriori from the variety and degrees of perfection in things, and the order of causes and effects, from the intelligence that created beings are confessedly endowed with, and from the beauty, order, and final purpose of things." The theses maintained in the argument are:

In order to establish his sixth thesis, Clarke contended that time and space, eternity and immensity, are not substances, but attributes: the attributes of a self-existent being.

The work of Clarke on the existence of God set off a British debate that lasted to the middle of the century. Edmund Law and other writers represented Clarke as arguing from the existence of time and space to the existence of Deity. Law was influenced by a 1718 work of Samuel Colliber that modified Clarke's approach.