Jean Leray
Jean Leray (7 November 1906-10 November 1998) was a French mathematician, who worked on both partial differential equations and algebraic topology. He was born in Nantes.His main work in topology was carried out while he was in a prisoner of war camp in Austria during 1940-1945. It originated together the ideas of spectral sequence and sheaf. These were subsequently developed by many others, each separately becoming an important tool in homological algebra.