Sergei Alexandrovich Yesenin (sometimes spelled as Esenin; Russian: Серге́й Алекса́ндрович Есе́нин; IPA: [sʲɪrˈgʲej ɐlʲɪkˈsandrəvʲɪtɕ jɪˈsʲenʲɪn]; 3 October [O.S. 21 September] 1895 – 28 December 1925) was a Russian lyrical poet. He was one of the most popular and well-known Russian poets of the 20th century.

Sergey Esenin was born in Konstantinovo in the Ryazan Province (Губерния, Gubernia) of the Russian Empire to a peasant family. He spent most of his childhood with his grandparents, who essentially reared him. He began to write poetry at the age of nine.

In 1912, Esenin moved to Moscow, where he supported himself working as a proofreader in a printing company. The following year he enrolled in Moscow State University as an external student and studied there for a year and a half. His early poetry was inspired by Russian folklore. In 1915, he moved to St. Petersburg, where he became acquainted with fellow-poets Alexander Blok, Sergey Gorodetsky, Nikolai Klyuev and Andrei Bely. It was in St. Petersburg that he became well known in literature circles. Blok was especially helpful in promoting Yesenin's early career as a poet. Yesenin said that Bely gave him the meaning of form while Blok and Klyuev taught him lyricism.