Alexei Nikolayevich Kosygin (Russian: Алексе́й Никола́евич Косы́гин, tr. Aleksej Nikolajevič Kosygin; IPA: [ɐlʲɪˈksʲej nʲɪkɐˈlajɪvʲɪtɕ kɐˈsɨɡʲɪn]; 21 February [O.S. 8 February] 1904 – 18 December 1980) was a Soviet-Russian statesman during the Cold War. Kosygin was born in the city of Saint Petersburg in 1904 to a Russian working-class family. He was conscripted into the labour army during the Russian Civil War, and after the Red Army's demobilisation in 1921, he worked in Siberia as an industrial manager. Kosygin returned to Leningrad in the early 1930s and worked his way up the Soviet hierarchy. During the Great Patriotic War (World War II), Kosygin was a member of the State Defence Committee and was tasked with moving Soviet industry out of territories soon to be overrun by the German Army. He served as Minister of Finance for a year before becoming Minister of Light Industry and later, the Minister of Light and Food Industry. Stalin removed Kosygin from the Politburo one year before his own death in 1953, intentionally weakening Kosygin's position within the Soviet hierarchy.

After the power struggle triggered by Stalin's death in 1953, Nikita Khrushchev became the new leader. On 20 March 1959, Kosygin was appointed to the position of Chairman of the State Planning Committee (Gosplan), a post he would hold for little more than a year. Kosygin next became First Deputy chairman of the Council of Ministers. When Khrushchev was replaced in 1964, Kosygin and Leonid Brezhnev became Premier and First Secretary respectively. Kosygin, along with Brezhnev and Nikolai Podgorny, the Chairman of the Presidium of the Supreme Soviet, was a member of the newly established collective leadership. Kosygin became one of two major power players within the Soviet hierarchy, the other being Brezhnev, and was able to initiate the failed 1965 economic reform, usually referred to simply as the Kosygin reform. This reform, along with his more open stance on solving the Prague Spring (1968), made Kosygin one of the most liberal members of the top leadership.

More conservative members of the top leadership saw some of Kosygin's policies as too radical, but they were never able to depose him as Premier, even if he and Brezhnev disliked each other. By the 1970s, Brezhnev had consolidated enough power to stop any "radical" reform-minded attempts by Kosygin. In 1980, Kosygin retired from office due to bad health, dying two months later on 18 December 1980.