Ivan Pavlov, Ilya Mechnikov, Ivan Michurin, Ivan Sechenov, Nikolai Vavilov, Nikolay Pirogov, Leonhard Euler, Mikhail Lomonosov, Vladimir Obruchev, Sofia Kovalevskaya, Aleksander Stoletov, Alexander Popov, Nikolai Lobachevsky, Grigori Perelman, Zhores Alferov, Nikolay Basov, Vitaly Ginzburg, Abram Ioffe, Pyotr Kapitsa, Igor Kurchatov, Lev Landau, Alexander Prokhorov, Andrei Sakharov, Nikolay Semyonov, Nikolay Zhukovsky, Aleksandr Butlerov, Dmitri Mendeleyev, Sergei Korolyov, Pavel Sukhoi, Alexei Tupolev, Yevgeny Kaspersky
You may know Russian-born American scientist Vladimir Zworykin.
Mendeleev created the Periodic table we all know and use today. Tsiolkovsky discouvered reactive power which allowed us to start building spaceships and rocket engines. And many others I'm lazy to remember.