Harold Adrian Russell "Kim" Philby (1 January 1912 – 11 May 1988) was a British intelligence officer and a double agent for the Soviet Union. In 1963, he was revealed to be a member of the Cambridge Five, a spy ring that had divulged British secrets to the Soviets during World War II and in the early stages of the Cold War. Of the five, Philby is widely considered to have been the most successful in providing secret information to the Soviets.
Born in British India, Philby was educated at Westminster School and Trinity College, Cambridge. He was recruited by Soviet intelligence in 1934, while he was studying at Cambridge. After leaving Cambridge, Philby worked as a journalist, covering the Spanish Civil War and the Battle of France. In 1940, he began working for the United Kingdom's Secret Intelligence Service (SIS or MI6). By the end of the Second World War he had become a high-ranking member.
In 1949, Philby was appointed first secretary to the British Embassy in Washington and served as chief British liaison with American intelligence agencies.