William Bowen Bonnor (9 September 1920 – 17 August 2015) was a mathematician and gravitation physicist best known for his research into astrophysics, cosmology and general relativity. For most of his academic career he was a professor of mathematics at the University of London. William Bonnor was born in London on 13 September 1920. He was educated at County High School, Ilford, at South East Essex Technical College and at Birkbeck College. His degrees of B.Sc., Ph.D. and D.Sc. were all obtained by part-time study. William Bonnor died at his home of a heart attack on 17 August 2015.