Thomas Rees (1777 – 1 August 1864), Welsh Nonconformist divine, was a Unitarian minister and scholar.
Rees was educated at the Presbyterian College, Carmarthen. He entered the Unitarian ministry in 1807 at the Newington Green Unitarian Church, London. He went to Southwark in 1813, earned the degree of LL.D. of Glasgow in 1819, and went to Stamford Street, Blackfriars, in 1823.
He had great knowledge of the history of anti-trinitarian opinion, especially of the 16th century. He published papers, chiefly in the Monthly Repository between 1818 and 1822, on such subjects as Faustus Socinus and Francis David, including The Italian Reformation, Memoirs of the Socini. Financial troubles drove him to Spain in 1853, and he died in obscurity in Brighton.
He was born in Gelligron, Glamorgan, the son of Josiah Rees; George Owen Rees was his nephew. He started in the bookselling business, but on the advice of Abraham Rees (no relation), he was educated for the ministry (1799–1801) at Carmarthen College.
In 1807 Rees became afternoon preacher at Newington Green Chapel, London, of which he had sole charge from 1808 to 1813, when he moved to St. Thomas's Chapel, Southwark, which was closed in 1822. On 12 October 1823 a new chapel was opened in Stamford Street, Blackfriars, London, built from the proceeds of the sales of St. Thomas's Chapel and the chapel in Prince's Street, Westminster. Here Rees ministered till 1831, when he ceased to hold regular ministerial charge.