Klaus Fuchs — German Physicist born on December 29, 1911, died on January 28, 1988
Emil Julius Klaus Fuchs was a German-born British theoretical physicist and atomic spy who, in 1950, was convicted of supplying information from the American, British, and Canadian Manhattan Project to the Soviet Union during and shortly after the Second World War. While at the Los Alamos National Laboratory, Fuchs was responsible for many significant theoretical calculations relating to the first nuclear weapons, and later, early models of the hydrogen bomb... (wikipedia)