Orfeo ed Euridice (French version: Orphée et Eurydice; English: Orpheus and Eurydice) is an opera composed by Christoph Willibald Gluck based on the myth of Orpheus, set to a libretto by Ranieri de' Calzabigi. It belongs to the genre of the azione teatrale, meaning an opera on a mythological subject with choruses and dancing. The piece was first performed at the Burgtheater in Vienna on 5 October 1762 in the presence of Empress Maria Theresa. Orfeo ed Euridice is the first of Gluck's "reform" operas, in which he attempted to replace the abstruse plots and overly complex music of opera seria with a "noble simplicity" in both the music and the drama.