Aleksandr Ilyich Leipunskii (Russian: Алекса́ндр Ильи́ч Лейпу́нский; Ukrainian: Олександр Ілліч Лейпунський; 7 December 1903 – 14 August 1972) was a Soviet physicist.
He then joined the Leningrad Physico-Technical Institute, where he studied atomic interactions with electrons and molecules.
In September 1937 Leipunskii was arrested as a German spy in connection with the UPTI Affair, but later released.
After being evacuated to Ufa, in 1941 he also became a head of the Institute of Physics of the Academy of Sciences of the Ukrainian SSR and held that post until 1949.
Following the war, he played a significant role in the development of nuclear power in the Soviet Union.