Soviet Union usually had a de facto leader who would not necessarily be head of state but would lead while holding an office such as Premier or General Secretary. Under the 1977 Constitution, the Chairman of the Council of Ministers, or Premier, was the head of government and the Chairman of the Presidium of the Supreme Soviet was the head of state. Take a look on the list of USSR leaders of such a powerful country.
Vladimir Ilyich Ulyanov (22 April 1870 – 21 January 1924), better known by his alias Lenin, was a Russian revolutionary, politician, and political theorist. He served as head of government of Soviet Russia from 1917 to 1922 and of the Soviet Union from 1922 to 1924. Under his administration, Russia and then the wider Soviet Union became a one-party communist state governed by the Russian Communist Party. Ideologically a communist, he developed a variant of Marxism known as Leninism; his ideas were posthumously codified as Marxism–Leninism.
Joseph Vissarionovich Stalin born in 18 December 1878 – 5 March 1953) was a Georgian revolutionary and Soviet politician who led the Soviet Union from the mid–1920s until 1953 as General Secretary of the Communist Party of the Soviet Union (1922–1953) and Premier (1941–1953). Initially presiding over a collective leadership as first among equals, by the 1930s he was the country's de facto dictator. A communist ideologically committed to the Leninist interpretation of Marxism, Stalin helped to formalize these ideas as Marxism–Leninism, while his own policies became known as Stalinism.
Mikhail Sergeyevich Gorbachev (born 2 March 1931) is a Russian and formerly Soviet politician. The eighth and last leader of the Soviet Union, he was General Secretary of its governing Communist Party from 1985 until 1991. He was the country's head of state from 1988 until 1991, serving as Chairman of the Presidium of the Supreme Soviet from 1988 to 1989, Chairman of the Supreme Soviet from 1989 to 1990, and President of the Soviet Union from 1990 to 1991. Ideologically, he initially adhered to Marxism-Leninism although by the early 1990s had moved toward social democracy.