Mark Andreyevich Natanson (Russian: ???? ?????´???? ???????´?; Party name: Bobrov) (25 December 1850 (N.S.
6 January 1851) – 29 July 1919) was a Russian-Jewish revolutionary and one of the founders of the Circle of Tchaikovsky, Land and Liberty, and the Socialist-Revolutionary Party.
In 1917, he was a leader of the Left Socialist-Revolutionaries, supporting the Bolsheviks in the October Revolution.