Sergey Dmitrievich Mstislavsky (Сергей Дмитриевич Мстиславский, born Maslovsky; November 4, 1876, Moscow - April 22, 1943, Irkutsk, USSR) was a Russian Soviet writer, dramatist, publicist, anthropologist, editor and political activist, close to the Left Socialist-Revolutionaries.

In the 1920s and 1930 he authored numerous adventure novels, mostly about the events of the 1905 and 1917 Revolutions and the Russian Civil War (Built on Blood, 1927; The Heavy Cavalry Alliance, 1928; The Partions, 1932; The Eve.

While a student he took part in several expeditions to the Central Asia; as a result, the series of stories and sketches ("On the Margins", "In Samarkand", "Kop-Kara" and others) came out in 1900.

Some critics praised the author's well-structured, intricate plotlines, others accused him of being perfunctory when portraying the real people or accounts of political events.

[1] Among his later works were historical novels The Partions (1932, on Narodnaya Volya), Black Magoma (1932, building of Socialism in Avaria in the Caucasus), Rook is the Bird of Spring (1936, on Nikolay Bauman), The Eve.