4. Richard Sorge
Richard Sorge was the Soviet spy in Japan during the Second World War and was considered as the best spy of his times. He was sent on various missions as a journalist to gather information about the communist uprisings and other information. He was sent to Japan in 1933 where he successfully gathered a lot of information. However, he was arrested in 1941 by the Japanese authorities. He denied all allegations of spying for the Soviets. However he was hanged in 1944.