Klaus Fuchs was a German-born physicist who played a significant role in the development of nuclear weapons during World War II. He worked on the Manhattan Project in the United States, contributing to the creation of the atomic bomb. Fuchs later moved to the United Kingdom, where he continued his work in nuclear physics. In 1950, Fuchs was arrested for espionage after it was revealed that he had been passing atomic secrets to the Soviet Union. He was convicted and sentenced to 14 years in prison, serving nine before his release. Fuchs' actions had a lasting impact on the Cold War and nuclear proliferation.