Oleg Vladimirovich Penkovsky (; 23 April 1919 – 16 May 1963), codenamed Hero (by the CIA) and Yoga (by MI6) was a Soviet military intelligence (GRU) colonel during the late 1950s and early 1960s. Penkovsky informed the United States and the United Kingdom about Soviet military secrets, including the appearance and footprint of Soviet intermediate-range ballistic missile installations and the weakness of the Soviet intercontinental ballistic missile (ICBM) program. This information was decisive in allowing the US to recognize that the Soviets were placing missiles in Cuba before most of them were operational. It also gave US President John F. Kennedy, during the Cuban Missile Crisis that followed, valuable information about Soviet weakness that allowed him to face down Soviet leader Nikita Khrushchev and resolve the crisis without a nuclear war. Wikipedia
Who is popular today?