Eva Le Gallienne (January 11, 1899 – June 3, 1991) was an American stage actress, producer, director, translator, and author. A Broadway star by age 21, in 1926 she left Broadway behind to found the Civic Repertory Theatre, where she served as director, producer, and lead actress. Noted for her boldness and idealism, she was a pioneering figure in the American theater, setting the stage for the Off-Broadway and regional theater movements that swept the country later in the 20th century.

Le Gallienne devoted herself to the art of the theater as opposed to the show business of Broadway. She felt strongly that high-quality plays should be affordable and accessible to all people who wanted to see them. She ran the Civic Repertory Theatre for seven years (1926–1934), producing 37 plays during that time with a company whose actors included Burgess Meredith, John Garfield, Norman Lloyd, J. Edward Bromberg, Paul Leyssac, Florida Friebus, David Manners, Josephine Hutchinson, Alla Nazimova, Joseph Schildkraut, and Leona Roberts.

Le Gallienne was born in London to Richard Le Gallienne, an English poet of French descent, and Julie Nørregaard, a Danish journalist. They married in 1897 and separated in 1903, later divorcing. Le Gallienne and her mother spent the next eleven years shuttling between Paris, London, and Copenhagen.

While in Paris, Le Gallienne was taken to see performances by Sarah Bernhardt. She idolized the actress and sought to emulate her. Meeting "La Grande Sarah" as a young girl inspired Le Gallienne to devote herself to "the power of the Theatre to spread beauty out into life."

Le Gallienne made her stage debut at the age of 15 with a walk-on role in a 1914 production of Maurice Maeterlinck's Monna Vanna. She spent several months attending drama school at Tree's Academy (now the Royal Academy of Dramatic Art). She left school to perform in the role of a cockney servant in a West End play called The Laughter of Fools, and "brought down the house", receiving excellent reviews.

The next year, at age 16, Le Gallienne and her mother sailed for New York City, where she began auditioning for Broadway plays. Her first few roles were small, and she struggled for recognition. She spent a season performing on tour and in summer stock. After traveling in Europe for a period of time, she returned to New York to star in Arthur Richman's Not So Long Ago (1920).

Soon afterward, she became a full-fledged Broadway sensation playing the role of Julie in Ferenc Molnár's Liliom (1921) for the Theatre Guild. She became known as a star in 1923 when she played Princess Alexandra in Molnar's The Swan. Le Gallienne became a naturalized United States citizen in 1927.

Le Gallienne's great dream was to found a classical repertory theatre like those of the European cities in which she grew up. After producing and directing some special matinees of plays by Henrik Ibsen, in 1926 she leased a theatre on West Fourteenth Street in Manhattan. There she established the Civic Repertory Theatre. Her goal was to present the highest quality plays at the lowest possible prices. Her motto was, "The theatre should be an instrument for giving, not a machinery for getting."