Mikhail Gorbachev
Mikhail Sergeyevich Gorbachev (born 2 March 1931) became Secretary General of the Communist Party of the Soviet Union on March 11, 1985 and the de facto leader of the USSR. His rise to leadership is generally seen as the beginning of the end of the Soviet empire in 1991.
When Gorbachev was appointed, he was the youngest member of the Politburo and succeeded Konstantin Chernenko (1911–1985), who had died of emphysema the day (March 10) before Gorbachev's appointment. Gorbachev is best known for his policy of perestroika (reform) and glasnost (transparency). His attempts to reform the Communist Party led to the end of the Cold War—for which he received the Nobel Peace Prize of 1990—and to the end of the omnipotence of the Communist Parties in the Soviet Republics. This, in turn, caused the dissipation of the Union of Socialist Soviet Republics in 1991, the year of abdication of Gorbachev.