Margaretha Geertruida "Margreet" MacLeod, better known by the stage name Mata Hari, was a Dutch exotic dancer and courtesan who was convicted of being a spy for Germany during World War I and executed by firing squad in France.
Gina Cheri Haspel is an American intelligence officer serving as Director of the Central Intelligence Agency (CIA) since 2018. She is the first woman to hold the post on a permanent basis and had been previously the Deputy Director under Mike Pompeo in the beginning of the presidency of Donald Trump.
Virginia Hall Goillot was an American spy with the British Special Operations Executive during World War II and later with the American Office of Strategic Services and the Special Activities Division of the Central Intelligence Agency. She was known by many aliases, including "Marie Monin", "Germaine", "Diane", "Marie of Lyon", "Camille", and "Nicolas". The Germans gave her the nickname Artemis. The Gestapo reportedly considered her "the most dangerous of all Allied spies".
Emil Julius Klaus Fuchs was a German 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. After nine years' imprisonment in Great Britain, he re-migrated to the German Democratic Republic where he resumed his career as a physicist and scientific leader. 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.
A sleeper agent is a spy who is placed in a target country or organization not to undertake an immediate mission but to act as a potential asset if activated. Even if unactivated, the "sleeper agent" is still an asset and is still playing an active role in sedition, treason or espionage by virtue of agreeing to act if activated. Sleeper agents are popular plot devices in fiction, particularly in espionage fiction and science fiction. This common use in fiction is directly related to and results from repeated instances of real-life "sleeper agents" participating in spying, espionage, sedition, treason, and assassinations.
Guy Francis de Moncy Burgess was a British diplomat and Soviet agent, a member of the Cambridge Five spy ring that operated from the mid-1930s to the early years of the Cold War. His defection in 1951 to the Soviet Union, with his fellow-spy Donald Maclean, led to a serious breach in Anglo-American intelligence co-operation, and caused long-lasting disruption and demoralisation in Britain's foreign and diplomatic services.
In the field of counterintelligence, a double agent is an employee of a secret intelligence service for one country, whose primary purpose is to spy on a target organization of another country, but who, in fact, has been discovered by the target organization and is now spying on their own country's organization for the target organization.
Christopher David Steele is a former British intelligence officer with the Secret Intelligence Service MI6 from 1987 until his retirement in 2009. He ran the Russia desk at MI6 HQ in London between 2006 and 2009. In 2009 he co-founded Orbis Business Intelligence, a London-based private intelligence firm. He authored a dossier that claims Russia collected a file of compromising information on U.S. President Donald Trump.
In Ian Fleming's James Bond novels and the derived films, the 00 Section of MI6 is considered the secret service's elite. A 00 is a field agent that holds a licence to kill in the field, at his or her discretion, to complete any mission. The novel Moonraker establishes that the section routinely has three agents concurrently; the film series, beginning with Thunderball, establishes the number of 00 agents at a minimum of 9, with the likelihood of more.