The prominent Russian mathematician Sergei Mikhailovich Nikol’skii, scholar, educator, organizer of science, and academician of the Russian Academy of Sciences, passed away on 9 November 2012, in his 108th year. Sergei Mikhailovich had a long and exemplary life. He was born at Zavod Talitsa in Perm’ Province (now Talitsa in Perm’ Oblast) on 30 April 1905. His father, Mikhail Dmitrievich Nikol’skii, held the rank of forestry specialist 1st class, and worked as a forest warden in Voronezh Province after the October Revolution. He was killed by bandits in 1921. Sergei’s mother, Lyudmila Mikhailovna, was a village teacher. In his teens Sergei began working in forestry, and later at a state farm. After Mikhail’s death the Nikol’skii family moved to Chernigov, where Sergei worked in provincial political education and studied at the Industrial and Agronomical Technical College. In 1925 he was admitted to the Institute of Public Education at Ekaterinoslav (now Dnepropetrovsk), and already during his first year there he became seriously interested in mathematics. In 1929 Nikol’skii was kept on at the Institute as an assistant professor. He regularly attended lectures delivered by A. N. Kolmogorov and P. S. Alexandrov, professors at Moscow State University who periodically visited Dnepropetrovsk. Soon he became one of Kolmogorov’s students, and found in him not merely a scientific advisor but also a general mentor. In 1934–1935 Nikol’skii was sent to Moscow State University to work on his Ph.D. dissertation. He studied, in his own words, from nine o’clock in the morning till nine o’clock in the evening, attending the seminars of Kolmogorov, V. L. Goncharov, A. I. Plessner, L. A. Lyusternik, and others. After defending in 1935 his dissertation on linear equations in Banach spaces, he became head of the Department of the Theory of Functions at Dnepropetrovsk University. The seminar he led there is now regarded as the origin of the Dnepropetrovsk school on the theory of approximation of functions. In January 1941 he became a postdoctoral researcher at the Steklov Mathematical Institute. Before the Second World War he completed work for his D.Sc. degree.