The Pirates of Penzance, or The Slave of Duty, is a comic opera in two acts, with music by Arthur Sullivan and libretto by W.S. Gilbert.

It is one of the Savoy Operas. The official premiere was at the Fifth Avenue Theatre in New York on December 31, 1879, where it was a hit with audiences and critics. The London premiere was on April 3, 1880, at the Opera Cornique, where it ran for 363 performances, having already been playing successfully for over three months in New York.