William Couper was an American entomologist and naturalist, believed to be born in Sheldon, Vermont.

Nothing is known of his early life, although he is believed to have arrived in Toronto, Ontario in 1843. He worked as a typographer in the printing shop of Henry Rowsell. He seems to have followed this trade for much of his life, as well as giving private instruction in taxidermy. From 1842 to 1859, he wrote many articles and notes on birds which were published particularly in Canadian and American periodicals. A conference by Henry Holmes Croft, a University College teacher, spurred him into collecting his first specimens. After a brief stay at Trois-Rivières in 1860, he lived in Quebec City until 1869, in Ottawa from 1869 to 1870, and in Montreal from 1871 to 1884. He became a corresponding member of the Entomological Society of Philadelphia, and in 1864, a year after the Entomological Society of Canada was organized in Toronto, he helped establish a branch in Quebec City. In 1873, he became a founder and first president of the Montreal branch of the society. It continued to develop steadily, and in 1951 became known as the Entomological Society of Quebec. While in Quebec, Couper made two collecting trips to Labrador (1867, 1872) and one to the island of Anticosti, Quebec. His collections of about 6000 specimens were noticed and praised in The Canadian Journal. In the late 1860s and at least to March of 1871, Couper served as Assistant Curator and Taxidermist for The Literary and Historical Society of Quebec. He apparently lived at 38 Bonaventure Street, Montreal. In 1873, he decided to set up as an independent taxidermist and established himself at 67 Bonaventure Street in Montreal. His discussions of insects harmful to crops, such as the apple borer, the cabbage butterfly, and the onion fly were published in the Canadian Entomologist, the Canadian Naturalist and Geologist and other publications. Couper also established a list of the Hymenoptera found on Montreal Island, and took a special interest in Coleoptera, publishing taxonomical descriptions of 15 new species. In 1881, he began The Canadian Sportsman and Naturalist, a journal published in Montreal for three years, focused particularly on types of game in Canada as well as hunting and fishing regulations. In 1884, he moved to New York City where he lived up to 1886.

He probably died at his son’s residence in Troy, N.Y., about 1890.