Mark Aronovich Naimark (Russian: Марк Ароно́вич Наймарк) (5 December 1909 – 30 December 1978) was a Soviet mathematician. He was born in Odessa, Russian Empire (today's Ukraine) into a Jewish family and died in Moscow, USSR. He received his PhD in 1943 from the Steklov Institute of Mathematics; his doctoral advisor was Mark Krein. In 1962 he became professor in the Department of the Theory of Functions and Functional Analysis at the Steklov Mathematical Institute.