Theater & Orchester Heidelberg, Opera house and theater in Heidelberg, Germany.

Theater and Orchestra Heidelberg is an opera and theater house with multiple performance spaces, including the Alter Saal and Zwinger stages. It offers opera, drama, dance productions, concerts and children's theater.

The late classicist building was designed and opened in 1853 by city architect Friedrich Lendorf. It marked the beginning of professional theater in Heidelberg.

The Heidelberger Stückemarkt, held here since 1984, is one of Germany's long-standing festivals for contemporary theatre, with a changing guest country and a competition for emerging playwrights. Since 2011 the follow-up festival Don't Believe the Hype has staged second productions of new plays.

The two main stages, the Marguerre-Saal and the Alter Saal, have separate entrances for the audience. The Marguerre-Saal seats about 600, the Marguerre-Saal 550 according to older figures; smaller productions run at Zwinger 1 and Zwinger 3. All workshops, the orchestra and choir rehearsal room and four rehearsal stages sit under one roof.

The house holds more festivals in one season than any other German theatre: the Heidelberger Stückemarkt for contemporary drama, the Schlossfestspiele in the castle courtyard, the baroque festival Winter in Schwetzingen, and every second year the Ibero-American festival ¡Adelante! and a dance biennale.