Mark Aronovich Naimark () (5 December 1909 – 30 December 1978) was a Soviet mathematician who made important contributions to functional analysis and mathematical physics. Life Naimark was born on 5 December 1909 in Odessa, part of modern-day Ukraine, but which was then part of the Russian Empire. His family was Jewish, his father Aron Iakovlevich Naimark a professional artist, and his mother Zefir Moiseevna. He was four years old at the onset of World War I in 1914, and seven when the tumultuous Russian Revolution began in 1917. Showing an early talent for mathematics, Naimark enrolled in a technical college at the age of fifteen in 1924 soon after the Russian Civil War had ended. There he studied while working at a foundry until enrolling in the Physics and Mathematics faculty at Odessa Institute of National Education in 1929. He married his wife Larisa Petrovna Shcherbakova in 1932, with whom he had two sons. In 1933, Naimark began graduate studies at Odessa State University in the Department of the Theory of Functions. He was supervised by the functional analyst Mark Krein, completing his candidate's dissertation in 1936. Krein was at the time still a young mathematician, only two years older than Naimark, but had already built a research group in functional analysis, and they worked together on some Naimark's first works on symmetric and Hermitian forms. In 1938 Naimark began his doctoral studies at the Steklov Institute of Mathematics, where he developed his renowned work on self-adjoint extensions of symmetric operators, and began a collaboration with Israel Gelfand that lasted for over a decade. He received his doctorate in 1941, and was made a chair at the Seismological Institute of the USSR Academy of Sciences. In 1941 Hitler invaded the Soviet Union, and in the same year the Romanian and German occupation of the Ukraine led to the 1941 Odessa massacre in Naimark's hometown. Naimark joined special duty (called "home-guard") during the war and worked on the labor front, moving to Tashkent with the Seismological Institute at the end of 1941 as the Nazi army advanced on Moscow, where he remained until 1943. After the war Naimark returned to Moscow, where he worked in various institutes, and in 1954 became a professor in the Department of Mathematics at the Physico-Technical Institute of Moscow. He was appointed a professor at the Steklov Institute of Mathematics in 1962, where he stayed