Epic theatre, also known as theater of alienation, or theater of politics, is a theater movement arising in the early to mid-20th century, inextricably linked to Bertolt Brecht. Though many of the concepts involved in epic theater had been around for years, even centuries, Brecht unified them, developed the style, and popularized it.

Epic theatre works off the concept of Verfremdungseffekt, which translates as alienation effect or maybe estrangement effect. The purpose of this effect is to distance the audience from the characters and constantly reminded that what they are seeing is not real. Brecht felt that most theater's intent was to make the audience forget that the play was not real; however, he hoped to prevent this suspension of disbelief. By keeping the audience from identifying with the characters, Brecht hoped instead to cause them to think about the issues raised in the play. The alienation effect was achieved through such methods as actors directly addressing the audience out of character, set pieces and props being replaced by large labels ("TREE"), and the playing of harsh, discordant music intended to jar the audience out of complacency.

Another important element of the Epic Theatre is the Gestus. Bertolt Brecht invented this word to refer to the physical attitude or gesture that presents the character's actual state independent of the text. Brecht came up with the concept of Gestus from observing chinese acting. He noted that when the actor Mei Lan Fang acted a part which required his character to be frightened, he merely put a lock of his hair into his mouth and everyone in the audience knew that the character was scared. The actor, however remained completely calm throughout the performance. With a Gestus that clearly defines the character's attitude, the actor stays distanced from the play and therefore avoids any undue emotionality.

Epic theatre presents a situation and two sides of an argument. Brecht's concept of the Epic theatre was to force the audience to think about an issue and make a judgment. Late in his career, Brecht presented a different term for Epic Theatre. His new terminology was "Dialectic Theatre." This terminology emphasizes the argument and discussion presented in Epic plays.