The Margravial Opera House or Margrave's Opera House is a Baroque opera house in the town of Bayreuth in Germany. It is one of Europe's few surviving theatres of the period and has been extensively restored. It was built between 1744 and 1748 by Joseph Saint-Pierre; the interior was designed by Giuseppe Galli Bibiena and his son Carlo of Bologna in the late Baroque style. Princess Wilhelmine of Prussia, wife of the Frederick, Margrave of Brandenburg-Bayreuth, participated here as writer, player, composer, actor and director. Today she features in a sound-and-light presentation for tourists.
The stage's great depth (27 metres) attracted Richard Wagner, who later had his Bayreuth Festspielhaus built north of the town.
Each September from the year 2000 to 2009, the theatre hosted the Bayreuther Baroque festival, with performances of early operatic rarities. The 2009 festival included performances of Andrea Bernasconi's festa teatrale, L'Huomo, to a libretto by the Margravine Wilhelmine.