Olga Arsenievna Oleinik (also as Oleĭnik) HFRSE (Russian: О́льга Арсе́ньевна Оле́йник) (2 July 1925 – 13 October 2001) was a Soviet mathematician who conducted pioneering work on the theory of partial differential equations, the theory of strongly inhomogeneous elastic media, and the mathematical theory of boundary layers.

Also she was member of several foreign academies of sciences, and earned several honorary degrees.

On 2 May 1985 Olga Oleinik was awarded the laurea honoris causa by the Sapienza University of Rome, jointly with Fritz John.

[1] She authored more than 370 mathematical publications and 8 monographs, as the sole author or in collaboration with others: her work covers algebraic geometry, the theory of partial differential equations where her work enlightened various aspects, elasticity theory and boundary layers theory.

She was an enthusiast and very active teacher, advising the thesis of 57 "candidates".