7 of the Greatest Spies Who Ever Lived: List of Famous Spies of All Time

6. Julius and Ethel Rosenberg

Started working as spies in 1942.

Husband and wife spies, Julius and Ethel Rosenberg were Russian spies living and working in America, but working for the Russians to be more precise. They have managed to gather over 1,000 highly confidential documents, that contained nuclear secrets, and forwarded them to the USSR. In 1942. Julius was recruited by the KGB, and soon after that he became one of the most effective Soviet spies that operated in the U.S.A. After the arrest in 1953, their spying careers ended. They were charged with espionage, and convicted to death by an electric chair. The couple was executed in an electric chair in Sing Sing prison.