Sarah Aaronsohn (1890 – October 9, 1917) was a member of Nili, a ring of Jewish spies working for the British in World War I, and a sister of notable botanist Aaron Aaronsohn. Sometimes she is referred to as the "heroine of Nili."
Alfred Redl (March 14, 1864 – May 25, 1913) was an Austrian officer who rose to head the counter-intelligence efforts of Austria-Hungary. He was one of the leading figures of pre-World War I espionage. His term in office was marked by innovation, and he used very high technology for the time to ensnare foreign intelligence agents. But he was himself a spy for the Russians.
Larry Wu-tai Chin (1922–February 22, 1986) was a former Chinese language translator working for the CIA's Foreign Broadcast Information Service. He sold classified documents to the People's Republic of China from 1952 to 1985.
Jan Willem (or Wilhelm) Ter Braak (originally Engelbertus Fukken) (died c. March 29, 1941) was a Dutch espionage agent working for Germany who operated for five months in the United Kingdom. Although his active period was short, Ter Braak is believed to have been the German agent who was at large for the longest time in Britain during the Second World War. When he ran out of money, Ter Braak committed suicide in a public air raid shelter.
Alexander Dmitrievich Ogorodnik was a Soviet Diplomat who, while stationed in Bogotá, was blackmailed by Colombian intelligence agents into spying against the Soviet Union. While he initially showed little promise and claimed he knew only of Colombian political affairs, he was later transferred to the Soviet Foreign Ministry in Moscow. In this new position he was able to photograph a great deal of secret diplomatic cables, many of which were sent daily to the White House.