Theophilus Lindsey (20 June 1723 O.S. – 3 November 1808) was an English theologian and clergyman who founded the first avowedly Unitarian congregation in the country, at Essex Street Chapel.
Lindsey was born in Middlewich, Cheshire, and was educated at the Leeds Free School and at St John's College, University of Cambridge, where in 1747 he became a fellow. For some time he held a curacy in Spitalfields, London, and from 1754 to 1756 he travelled on the continent of Europe as tutor to the young Duke of Northumberland.
He was then presented to the living of Kirkby-Wiske in Yorkshire, and after exchanging it for that of Piddletown in Dorsetshire, he moved in 1763 to Catterick in Yorkshire. Here about 1764 he founded one of the first Sunday schools in England.
Meanwhile he had begun to entertain anti-Trinitarian views, and to be troubled in conscience about their inconsistency with the Anglican belief; since 1769 the intimate friendship of Joseph Priestley had served to foster his scruples, and in 1771 he united with Francis Blackburne, archdeacon of Cleveland (his father-in-law), John Jebb (1736-1786), Christopher Wyvill (1740-1822) and Edmund Law 1703-1787), bishop of Carlisle, in preparing a petition to Parliament with the prayer that clergymen of the church and graduates of the universities might be relieved from the burden of subscribing to the thirty-nine articles, and "restored to their undoubted rights as Protestants of interpreting Scripture for themselves". Two hundred and fifty signatures were obtained, but in February 1772 the House of Commons declined even to receive the petition by a majority of 217 to 71; the adverse vote was repeated in the following year, and in the end of 1773, seeing no prospect of obtaining within the church the relief which his conscience demanded, Lindsey resigned as vicar.