Mikhail Gorbachev was the leader of the Soviet Union from 1985 to 1991. As General Secretary, he introduced wide-ranging reforms (glasnost and perestroika) which inadvertantly caused the collapse of communism in the USSR and Eastern Europe. Gorbachev resigned when the USSR was officially dissolved in late 1991.
"I like Mr. Gorbachev, we can do business together." - Margaret Thatcher