Rev William Greenfield FRSE DD (died 1827) was a Scottish minister, professor of rhetoric and belles lettres, literary critic, reviewer, and author whose career ended in scandal, resulting in him being excommunicated from the Church of Scotland, having his university degrees withdrawn, and his family assuming his wife's patronymic Rutherfurd.
He served as joint-minister of Edinburgh's High Kirk (1787–98), as Moderator of the General Assembly of the Church of Scotland (1796), and as Regius Professor of Rhetoric and Belles Lettres at Edinburgh University (1784–98). A friend and correspondent of Robert Burns and a beneficiary of Walter Scott, his lecture course in Rhetoric and Belles Lettres had a huge influence on the development of English Literature as a discipline in universities.
Greenfield was the third child, and second son of Captain John Greenfield, R.N. (d.1774) and Grizel Cockburn (dau. of Sir William Cockburn of that Ilk, 2nd Bart., 1662-1751). Baptised in Dalkeith Parish Church, Midlothian 9 Feb. 1755, he matriculated at Edinburgh University in 1774, graduating with MA on 17 April 1778, and was almost immediately (though unsuccessfully) nominated as a Professor of Mathematics at Marischal College, Aberdeen. He was ordained as a minister of the Church of Scotland to Wemyss Parish on 6 September 1781. He then moved to become the first minister of the new St Andrew's Church in the New Town of Edinburgh on 25 November 1784, until he was appointed Minister of St Giles (or High Kirk) of Edinburgh by the Town Council on 21 February, taking up post on 1 April 1787. He held this post as well as the Regius Professorship of Rhetoric and Belles Lettres (among the first University Chairs in English Literature in the world), which he had held in conjunction with Hugh Blair since 1784, and whom he succeeded. He was made Almoner to the King in March 1789. He "radically altered the size and structure of the Edinburgh course" he took over from Blair, according to Martin Moonie's chapter in Crawford's book. Greenfield had wide interest. He was a member of the Royal Society of Edinburgh, and on 12 April 1784 he read a paper and, later in its Transactions (1788 Vol 1, pp131–145) he published as an article entitled "On the use of negative quantities in the solution of problems by Algebraic Equations". (His son, Andrew Rutherfurd, attached a biographical note to his copy of this article, without revealing that the author was his father). Greenfield also delivered lectures in Natural Philosophy, the manuscripts of which are still retained Edinburgh University Library.