Thomson, Samuel Smith (1778?–1849), doctor and philanthropist, was one of at least four children of James Thomson, surgeon in Coleraine, and his wife Ellen, youngest daughter of Samuel Smith (1691–1760), who was prominent in Belfast, was related to many of Belfast's well known linen and merchant families, and was one of the founders of the Belfast Charitable Society. His son John Galt Smith (1731–1802?) was a leading businessman in Belfast, who was involved, among other things, with the city's ropeworks; John Galt Smith's son Samuel (fl. 1817) of Balnamore, Co. Antrim, was one of the pioneers of water-powered flax-spinning. James and Ellen Thomson had at least three daughters, as well as at least one son (Samuel); two sons of one of the daughters lived in later years with their uncle Samuel Thomson. One of them, James Bristow, was for many years director and manager of the Northern Banking company in Belfast.
After qualifying as a doctor, Samuel Thomson practised for some time in Magherafelt, but enjoyed more success in his career after he moved to Belfast. In 1801 he became visiting physician to the Belfast Charitable Society's Fever Hospital; he was also visiting physician to the Hospital for the Insane from February 1837. He withdrew temporarily from these posts on a couple of occasions, but each time was persuaded to return, and his involvement with the medical and other work of the Charitable Society lasted his whole life. A popular and much respected figure, he was one of the most active supporters of charities established in the city, and was involved with education also, helping promote the work of the Belfast Academical Institution. He was founder and first president of the Belfast Medical Society in 1806 and supported the establishment of another medical society in 1822, after a split in the original body. He suggested in 1841 that a new fever hospital be built, and himself contributed £50; work was well advanced on what became the Belfast General Hospital when the cholera epidemic of the late 1840s reached Belfast.
Thomson fell out with James MacDonnell (qv) during the prolonged and bitter controversy over whether dispensary doctors – and others ministering to disadvantaged members of the community – should receive salaries: Thomson, though he himself worked tirelessly without pay, felt that salaried doctors would provide a more professional and efficient service. In December 1834 he was presented with a gold snuffbox by thirty of his colleagues who agreed with his views.
Keenly interested in music, he was founder and for many years president of the Belfast Anacreontic Society, training its amateur musicians to a very high standard. After suffering for two years from bronchitis, he died 30 April 1849 at his home in Castle St., Belfast, and was buried in the New Burying Ground. Those who wrote of him afterwards did so in the most affectionate and admiring terms. A mural plaque in the First Presbyterian church in Belfast recorded his services to the congregation and the community. He was probably unmarried; his gravestone does not mention a wife or children, although it is worth noting that a Samuel Thomson married in the First Presbyterian church in 1826 and again in 1840.