Thomas Mullett (also Mullet) (1745–1814) was an English businessman and supporter of the American Revolution.
Mullett was a Quaker from Taunton, Devon, the son of Jane Mullet; Thomas Melhuish (c.1737–1802), a Quaker minister and shopkeeper, became his stepfather when his mother remarried. He left the Society of Friends on marrying. He moved to Bristol and there was involved with the Broadmead Baptist congregation, being secretary of the Bristol Education Society (founded 1770) that supported the local dissenting academy. He was a reformer and friend of Horatio Gates.
In Bristol, Mullett was in business as a stationer; and also by 1771 a papermaker, taking over from John Stock as the local manufacturer.
A friend of John Wilkes, Mullett became a leader of Bristol radicals, with Henry Cruger and Samuel Peach. In the 1774 general election, Cruger and Edmund Burke were elected as Bristol's Members of Parliament. Mullett wrote an account of the election with the Bristol list of voters published as The Bristol Poll-Book, but managed to offend Burke by identifying him too closely with Cruger. Burke was willing in 1779, however, to help Mullett release James Caton, a pro-American, from the press gang, with John Dunning applying under habeas corpus.
Jared Sparks conjectured that Mullett might have been the author of an unsigned letter from Bristol, to William Palfrey and containing intelligence, dated 16 February 1776. In British politics, Mullett favoured parliamentary reform; and he also supported the American Revolution. In 1778 he joined a Bristol committee for the relief of American prisoners. He travelled three times to America during his life. On his first American journey, just after the end of the American Revolutionary War, in 1783, he visited George Washington at Mount Vernon. He wrote to John Wilkes about his travels, from Charleston, South Carolina, on 15 February, describing how he had started from Portsmouth, New Hampshire, and the prospects of trade, with New York impressive; noting also the remaining strong feeling against some of the British military leaders from the war.