Carrington Bonsor Williams FRS (7 October 1889 – 12 July 1981) better known as C. B. Williams or just "C.B." to friends was an English entomologist and ecologist. His name is particularly associated with insect migration, statistical ecology and biogeography.
Born to Alfred Williams, a banker and Lillian Bonsor Williams (née Kirkland), he grew up in Liverpool and was not drawn to scientific interests by his parents, though he had access to books on natural history and kept an aquarium. He studied at a preparatory school in Cheshire and later at Birkenhead School from 1903 to 1908.
Around 1897 the family moved to the Cheshire coast where there were open fields. At the age of twelve, during a summer in Beddgelert he and his sister were introduced to the world of caterpillars by a local doctor. They were later taken to a meeting of the Lancashire and Cheshire Entomological Society. Williams name was put for membership and he was duly elected, although he learnt later that the members thought they were voting for his father.
He got a scholarship to Clare College, Cambridge University were his interests were in biology and he obtained a Diploma of Agriculture and a B.A. in 1911. He came in contact with William Bateson who was then studying caterpillars and had been appointed director of the John Innes Horticultural Institution, where Williams got a research studentship in applied entomology, working there for the next five years. He also visited the United States during this period, looking at agricultural entomology and meeting people such as T. H. Morgan, a close associate of Bateson. Williams worked during this period on the Thysanoptera, their biology and systematics and, along with J. D. Hood, described some new species.