President of the Soviet Union

The president of the Soviet Union (Russian: Президент Советского Союза, romanized: Prezident Sovetskogo Soyuza), officially the president of the Union of Soviet Socialist Republics (Президент Союза Советских Социалистических Республик), abbreviated as president of the USSR (Президент СССР), was the executive head of state of the Union of Soviet Socialist Republics from 15 March 1990 to 25 December 1991. Mikhail Gorbachev was the only person to occupy this office.

Source: Wikipedia — President of the Soviet Union (CC BY-SA 4.0)