Arthur Roy Clapham CBE, FRS (24 May 1904 – 18 December 1990), was a British botanist. Born in Norwich and educated at Downing College, Cambridge, Clapham worked at Rothamsted Experimental Station as a crop physiologist (1928–30), and then took a teaching post in the botany department at Oxford University. He was Professor of Botany at Sheffield University 1944–69 and vice chancellor of the university during the 1960s. He coauthored the Flora of the British Isles, which was the first, and for several decades the only, comprehensive flora of the British Isles published in 1952 and followed by new editions in 1962 and 1987. In response to a request from Arthur Tansley, he coined the term ecosystem in the early 1930s.