In a world that is fueled by success, competition and the idea of survival of the fittest, the role of double agents is never redundant. Double agents are known for bringing to the table their skills as intelligence operative; spies who pose as working for another agency while actually serving the organization they claim to be spying on. Clever strategy, huh? Hero and traitor all in the same sentence. Though this job is dangerous, double agents have been in existence for centuries. Here are some double agents of the past who definitely stand out.

1. Kim Philby

Kim Philby served as a British intelligence officer and a double agent for the Soviet Union. In 1934, he was recruited by Soviet intelligence. He worked for the United Kingdom’s Secret Intelligence Service, was the first secretary to the British Embassy in Washington and a chief British liaison with American Intelligence agencies. Philby was identified in 1963 as a member of the Cambridge Five, the group of spies who leaked British secrets to the Soviet Union during World War II in the early Cold War. Of the five, Philly is said to have had the greatest success to give the Soviets access to top-secret information.

2. Aldrich Ames

Aldrich Hazen Ames is a former CIA officer who became a KGB double agent. On February 21, 1994, Ames was arrested by the FBI on espionage charges. Ames was a thirty-one-year CIA veteran who had been spying for the Russians from 1985. He was suspected of compromising many CIA assets. He gave the Russians access to sensitive information regarding CIA and FBI human sources and technological operations aimed at the Soviet Union, through which he made millions. Ames is currently serving a life sentence with no possibility of parole.

3. Oleg Penkovsky

During the late 1950s and early 1960s, Oleg Penkovsky served as a colonel in the Soviet military intelligence (GRU). His actions significantly changed the course of history. Penkovsky revealed Soviet military secrets to the United States in the United Kingdom. Before and during the Cuban missile crisis of October 1962, the United States found great value in the information Penkovsky gave regarding the Soviet Union’s very limited capability in long-range missiles. On October 22, 1962, Penkovsky was arrested by the Soviets and was tried for treason.

4. James Rivington

James Rivington was an American journalist and the publisher of a “loyalist” newspaper known as Rivington’s Gazette. Later, he was the King’s Printer for New York. Rivington became a member of Culpher’s Spy Ring and worked closely with Robert Townsend a.k.a. Samuel Culpher Jr. He provided key information to General George Washington. However, after New York was evacuated and Rivington remained, he was no longer trusted by New Yorkers. By then people stopped supporting his business and it failed.

5. Robert Hansen

Robert Philip Hansen is a former FBI double agent from the United States. He worked against the United States from 1979 to 2001 as a spy for Soviet and Russian intelligence services. After joining the FBI, Hansen offered his services to the Soviet Main Intelligence Directorate and subsequently began his work as a spy. He remained anonymous to the Russians. Numerous classified documents detailing American nuclear war plans, advancements in military weaponry and facets of the country’s counter intelligence program were sold by Hansen to the KGB. The identities of the KGB spies working for the U.S were compromised. The Department of Justice referred to his spying as perhaps the worst intelligence disaster in U.S history.