Iosif Samuilovich Shklovsky (Ио́сиф Самуи́лович Шкло́вский) (July 1 1916 – March 3 1985) was a Russian astronomer and astrophysicist. His last name is sometimes given as Shklovskii or Shklovskij, and his first name is sometimes given as Josif or Josef.

He specialized in theoretical astrophysics and radio astronomy, as well as the Sun's corona, supernovas, and cosmic rays and their origins. He showed, in 1946, that the radio wave radiations from the sun emanate from the ionized layers of its corona, and he developed a mathematical method for discriminating between thermal and nonthermal radio waves in the Milky Way. He is noted especially for his suggestion that the radiation from the Crab Nebula is due to synchrotron radiation, in which unusually energetic electrons twist through magnetic fields at speeds close to that of light. Shklovsky proposed that cosmic rays from supernova explosions within 300 light years of the sun have been responsible for some of the mass extinctions of life on earth. His works include Physics of the Solar Corona (1966), Intelligent Life in the Universe (with Carl Sagan, 1968), and Supernovae (1969).

He won the Lenin Prize in 1960.

He was a Corresponding Member of Soviet Academy of Sciences beginning

in 1966.