Konstantin Sergeyevich Stanislavsky (Russian: Константин Сергеевич Станиславский) (January 17 [O.S. 5 January] 1863 – August 7, 1938), was a director and acting innovator, responsible for a great deal of the acting technique used during the 20th century, all over the world.
Stanislavsky was born Konstantin Sergeyevich Alexeyev in Moscow to a wealthy family in 1863. He came from a prosperous Russian family who manufactured gold and silver braiding for military decorations and uniforms. Marie Varley, his grandmother, was a touring French actress and the only member of his family from an artistic background. Stanislavsky had eight siblings, who joined the young boy in creating elaborate theatricals on birthdays and holidays. The family created its own amateur theatre and Stanislavsky frequently acted in these miniature shows, usually meant for birthdays or holidays. At eight years old, Stanislavsky became interested in the circus, and often directed and starred in his own imaginary circuses. Another passion for the young Stanislavsky was puppetry, where he put on scenes from The Corsair and The Stone Guest. With puppetry, he learned to hone in on his love of detail--a quality Stanislavsky would incorporate in his directing later on in life with the Moscow Art Theatre. At fourteen, Stanislavsky started what would be numbers of notebooks filled with observations, aphorisms and problems. As a blossoming actor, Stanislavsky would dress as a tramp and go down to railroad yards, or disguise himself as a gypsy. Konstantin took a firm decision, despite the opposition of his father, to study theatre.

Stanislavsky's System
Stanislavsky had different pupils during each of the phases of discovering and experimenting with a Universal System of acting. One such student, Ryszard Bolesławski, founded the American Laboratory Theatre in 1925. It had a tremendous impact on American acting, when one of Boleslawski's students, Lee Strasberg, went on to co-found The Group Theater (1931-1940) with Harold Clurman and Cheryl Crawford, the first American acting company to put Stanislavsky's first discoveries into theatrical practice. Boleslawski had been in Stanislavsky's class when experimenting with Affective Memory. Stanislavsky's theory later evolved to rely on Physical Action inducing feelings and emotions. Affective Memory is applied in Stanislavsky's System but not as much so as in Lee Strasberg's Method.
Stella Adler, the only American to study with Stanislavsky, was taught the Method of Physical Actions in Paris for five weeks in 1934. With this new knowledge she came to Lee Strasberg and introduced to him the new Method of Physical Actions. Strasberg understood the differences but rejected the Method of Physical Actions. He believed that acting was recollection of emotion. Adler said of Strasberg: "He got it all wrong."
Among the actors who have employed Stanislavsky's System in some form are Jack Nicholson, Marilyn Monroe, James Dean, Marlon Brando, Montgomery Clift, Harvey Keitel, Steve McQueen, Paul Newman, Warren Beatty, Robert Duvall, Johnny Depp, Sidney Poitier, Jessica Lange, William Hurt, Dustin Hoffman, Robert De Niro, Al Pacino, Gene Hackman, Kevin Spacey, Jane Fonda, Henry Fonda, Benicio Del Toro, Mark Ruffalo, Vincent D'Onofrio, Kate Winslet, Adrien Brody, Denzel Washington, Elizabeth Taylor, Hillary Swank,Sarah Nahapiet, Anthony Hopkins, and Sean Penn.
Charlie Chaplin said, "Stanislavky's book, An Actor Prepares, helps all people to reach out for big dramatic art. It tells what an actor needs to rouse the inspiration he requires for expressing profound emotions."
Sir John Gielgud said, "This director found time to explain a thousand things that have always troubled actors and fascinated students." Gielgud is also quoted as saying, "Stanislavsky's now famous book is a contribution to the Theatre and its students all over the world."
Stanislavsky's goal was to find a universally applicable approach that could be of service to all actors. Yet he said of his System, "Create your own method. Don't depend slavishly on mine. Make up something that will work for you! But keep breaking traditions, I beg you."
Stanislavsky's aim was to have all of his character's performed as real as possible. He was well known for the realism of his plays.