William Thompson (2 December 1805 – 17 February 1852) was an Irish naturalist celebrated for his founding studies of the natural history of Ireland, especially in ornithology and marine biology.

Thompson published numerous notes on the distribution, breeding, eggs, habitat, song, plumage, behaviour, nesting and food of birds.

Thompson's first scientific paper, The Birds of the Copeland Islands, was published in 1827 shortly after he joined the Belfast Natural History Society.

The interval between dinner and tea was given to the literature of the day and when the claims of local societies left him free he would retire to the study for two or three additional hours of scientific work.

Thompson either owned or had access to a very comprehensive ornithological library exemplared by the Ornithological Dictionary, Le Règne Animal, Selby's Illustrations of British Ornithology, Coenraad Jacob Temminck's Manuel d'ornithologie ou Tableau systématique des oiseaux qui se trouvent en Europe (Sepps & Dufour, Amsterdam, Paris 1815–40), William Edward Parry, 1821 Journal of a Voyage for the Discovery of a North-West Passage from the Atlantic to the Pacific; Performed in the years 1819–'20, in His Majecty's Ships Hecla and Griper ... with an Appendix Containing the Scientific and Other Observations London (1821), William Swainson and John Richardson, 1831.

[7] and The Natural History of Ireland is, in the section on birds, a Monograph with a literary style, sometimes anecdotal giving information on anatomy, plumage, behaviour, nesting and breeding, seasonality and distribution.

"[10] George Dickie's Flora of Ulster contains records of Thompson's frequent botanical contributions and his Hortus Siccus and he is mentioned in William Baird's Natural History of British Entomostraca.

Thompson corresponded extensively on all aspects of natural history with naturalists in both Britain and Ireland, including with zoologist Thomas Bell who was at the heart of the English scientific establishment and two of the "Grandees" of the Zoological Society, Nicholas Aylward Vigors, William Ogilby.

In 1852 Thompson died of a heart attack in London[11] where he had been tended by his friends William Yarrell, author of British Birds, Edward Forbes, Edwin Lankester, of the Ray Society and George Busk.

Excerpts from Thompson's letters and his notes were edited and published as the fourth volume of The Natural History of Ireland, which focused on invertebrates and non-avian vertebrates, by George Dickie, James Ramsey Garrett and Robert Patterson in 1856, four years after his death.