Let us not forget about --
Dmitri Mendeleev 19th century chemist who shaped the whole subject of Inorganic chemistry for the next 150 years
Lev Landau brilliant theoretical physicist of the middle of the 20th century.
Konstantin Tsiolkovsky, who was the grandfather of the successful Soviet space program.
Alexandr Borodin who not only did some important organic chemistry, but also wrote some pretty good music.
There are/were, of course, many others.