Mikhail Andreyevich Suslov (Russian: Михаи́л Андре́евич Су́слов; 21 November [O.S. 8 November] 1902 – 25 January 1982) was a Soviet statesman during the Cold War. He served as Second Secretary of the Communist Party of the Soviet Union from 1965, and as unofficial Chief Ideologue of the Party until his death in 1982. Suslov was responsible for party democracy and the power separation within the Communist Party. His hardline attitude toward change made him one of the foremost anti-reformist Soviet leaders.
During the Hungarian Revolution of 1956, Suslov, along with Anastas Mikoyan, operated in close proximity to Budapest in order to direct the activities of the Soviet troops and to lend assistance to the new Hungarian leadership. Suslov and Mikoyan attended the Politburo meeting of the Hungarian Socialist Workers' Party which elected János Kadar to the General Secretaryship. In a telegram to the Soviet leadership, Suslov and Mikoyan acknowledged that the situation had become more dire, but both were content with the dismissal of Ernő Gerő as General Secretary and the choice of Kádár as his successor. The Presidium of the Supreme Soviet criticised Suslov's and Mikoyan's concessions to the new revolutionary government in the People's Republic of Hungary. Despite his initial reservations, Suslov eventually supported the Presidium's decision to intervene in Hungary militarily and replace the counterrevolutionary government's leadership there.
More information on the English and Russian Wikipedia pages.