John Venn (9 March 1759 – 1 July 1813) was a priest of the Church of England and a central figure of the group of religious philanthropists known as the Clapham sect.
He was born at Clapham, then south-west of central London, while his father Henry Venn was curate there, on 9 March 1759. He entered Sidney Sussex College, Cambridge, graduated B.A. in 1781, and M.A. in 1784.
Venn was rector of Little Dunham, Norfolk, from 1783 to 1792, and rector of Clapham from 1792 to his death. He was one of the original founders of the Church Missionary Society in 1797, and was a leading abolitionist and philanthropist. He ran the school set up by the Society for the Education of Africans which was set up in Clapham in 1799. He died at Clapham on 1 July 1813. A volume of his sermons was published after his death.
Venn married first, at Trinity Church, Hull, on 22 October 1789, Catherine, daughter of William King, merchant, of Kingston upon Hull. By her he had sons Henry Venn, and John, for many years vicar of St. Peter's, Hereford; also five daughters, of whom Jane, the second, married James Stephen, and was mother of James Fitzjames Stephen and Leslie Stephen; and Caroline married Stephen Ellis Batten and was mother of Emelia Russell Gurney. He married, secondly, on 25 August 1812, Frances, daughter of John Turton of Clapham.
Venn was the father of Henry Venn (1796-1873), honorary secretary of the Church Missionary Society, and grandfather of logician and philosopher John Venn.