Thomas Gilliland (fl. 1804–1837) was a combative British journalist and theatre critic. According to attack pieces in The Satirist, or Monthly Meteor, he was "countenanced" by Matthew "Monk" Lewis and Thomas Moore, and frequented the green room of Drury Lane Theatre until Charles Mathews and other actors complained he was spying for scandalmonger Anthony Pasquin. Gilliland's 1806 pamphlet Diamond cut Diamond defended the future George IV, then Prince of Wales, against Nathaniel Jefferys's attack, for which the Prince gave him 500 guineas. In 1809, Mary Anne Clarke, the royal mistress of Prince Frederick, Duke of York and Albany was about to publish scandalous Memoirs, until Gilliland helped arrange a deal to buy and destroy the publishers' copies. Many attacks on the Duke were published the same year and erroneously rumoured to have been Clarke's memoirs. In 1810 Gilliland collaborated on The Rival Princes, a response to the attacks published in Clarke's name.In 1816 the Prince of Wales, now Prince Regent, granted Gilliland an annuity of £400, formalised by a contract of June 1817. In 1827, Gilliland bought what he claimed was a portrait of Shakespeare, an identification not otherwise supported.Edmund Henry Barker's Literary Anecdotes and Contemporary Reminiscences includes several he heard from Gilliland when both were imprisoned for debt in the Fleet in 1837.