Thomas Firmin (June 1632 – 1697) was an English businessman and philanthropist, publisher and unitarian member of the Church of England.
Henry Firmin was a parishioner of Samuel Ward, the Puritan incumbent of St. Mary-le-Tower, by whom in 1635 he was accused of erroneous tenets.
In 1676 he left the management of the concern in the hands of his nephew and partner, Jonathan James (son of his sister Prudence), who had been his apprentice; he was then worth about £9,000.
He kept it up to the day of his death, and nominally contrived to make it pay, by keeping the wages low, and supplementing them by private doles to his workers.
The higher rate of wages in woollen manufacture led Firmin to attempt its introduction as a London industry, in Artillery Lane.
From about 1676 he interested himself in the condition of prisoners for debt, freeing several hundreds who were detained for small sums, and successfully promoting acts of grace for the liberation of others.
In conjunction with his friend, Sir Robert Clayton, Firmin was an active governor of Christ's Hospital, carrying out improvements, of structure and arrangement.
In 1662 he raised money partly by "collections in churches" for the exiled anti-trinitarians of Poland; but when the Polish Calvinists met the same fate Firmin joined efforts for their relief.
Firmin was an original member of the Society for the Reformation of Manners (1691), and was very active in the enforcement of fines for the repression of profane swearing.
Books of this class known with certainty to have been promoted by him include the following: He never departed from the communion of the church of England, but put a Sabellian sense on the public forms.
Giles received his mother's portion and became a merchant; he married Rachel (d. 11 April 1724), daughter of Perient Trott and sister of Lady Clayton; died at Oporto on 22 January 1694, and was buried at Newport on 13 April; his widow afterwards married Owen Griffith, rector of Blechingley, Surrey.