Sergei Mikhailovich Eisenstein (Russian: Сергей Михайлович Эйзенштейн Sergej Mihajlovič Ejzenštejn; January 23, 1898 – February 11, 1948) was a revolutionary Soviet Russian film director and film theorist noted in particular for his silent films Strike, Battleship Potemkin and October, as well as historical epics Alexander Nevsky and Ivan the Terrible. His work vastly influenced early film makers owing to his innovative use of and writings about montage.

Eisenstein was born in Riga but his family moved frequently in his early years, reflecting his travels throughout his life. Eisenstein's father Mikhail Osipovich Eisenstein was of German-Jewish descent and his mother Julia Ivanovna Konetskaya, was from a Russian Orthodox family. He was born into a middle class family. His father was an architect and his mother was the daughter of a prosperous merchant. Julia left Riga the year of the 1905 Revolution, bringing Sergei with her to St. Petersburg. Sergei would return at times to see his father, who later moved to join them around 1910. Divorce followed this time of separation, with Julia deserting the family to live in France. At the Petrograd Institute of Civil Engineering, Sergei studied architecture and engineering, the profession of his father. At school with his fellow students however, Sergei would join the military to serve the revolution, which would divide him from his father. In 1918 Sergei joined the Red Army with his father Mikhail supporting the opposite side. This brought his father to Germany after defeat, and Sergei to Petrograd, Vologda, and Dvinsk. In 1920, Sergei was transferred to a command position in Minsk, after success providing propaganda for the October Revolution. At this time, Sergei studied Japanese—he learned some three hundred kanji characters which he cited as an influence on his pictorial development, and gained an exposure to Kabuki theatre, these studies led to travel to Japan. In 1920 Eisenstein moved to Moscow, and began his career in theatre working for Proletkult. His productions there were entitled Gas Masks, Listen Moscow, and The Wise Man, Eisenstein would then work as a designer for Vsevolod Meyerhold. In 1923 Eisenstein began his career as a theorist, by writing The Montage of Attractions for LEF. Eisenstein's first film, Glumov's Diary, was also made in this year with Dziga Vertov hired initially as an "instructor."

The Battleship Potemkin (1925) was acclaimed critically worldwide. But it was mostly his international critical renown which enabled Eisenstein to direct The General Line (aka Old and New), and then October (aka Ten Days That Shook The World) as part of a grand tenth anniversary celebration of the October Revolution of 1917. The critics of the outside world praised them, but at home, Eisenstein's focus in these films on structural issues such as camera angles, crowd movements and montage, brought him and likeminded others, such as Pudovkin and Dovzhenko, under fire from the Soviet film community, forcing him to issue public articles of self-criticism and commitments to reform his cinematic visions to conform to socialist realism's increasingly specific doctrines.