Konstantin Sergeyevich Stanislavski (; Russian: Константин Сергеевич Станиславский, IPA: [kənstɐnʲˈtʲin sʲɪrˈɡʲejɪvʲɪtɕ stənʲɪˈslafskʲɪj]; né Alekseyev; 17 January [O.S. 5 January] 1863 – 7 August 1938) was a seminal Russian and Soviet theatre practitioner. He was widely recognized as an outstanding character actor, and the many productions that he directed garnered him a reputation as one of the leading theatre directors of his generation. His principal fame and influence, however, rests on his "system" of actor training, preparation, and rehearsal technique.
Stanislavski (his stage name) performed and directed as an amateur until the age of 33, when he co-founded the world-famous Moscow Art Theatre (MAT) company with Vladimir Nemirovich-Danchenko, following a legendary 18-hour discussion. Its influential tours of Europe (1906) and the US (1923–24), and its landmark productions of The Seagull (1898) and Hamlet (1911–12), established his reputation and opened new possibilities for the art of the theatre. By means of the MAT, Stanislavski was instrumental in promoting the new Russian drama of his day—principally the work of Anton Chekhov, Maxim Gorky, and Mikhail Bulgakov—to audiences in Moscow and around the world; he also staged acclaimed productions of a wide range of classical Russian and European plays.