Gilbert and Sullivan was a Victorian-era theatrical partnership of the dramatist W. S. Gilbert (1836–1911) and the composer Arthur Sullivan (1842–1900), who jointly created fourteen comic operas between 1871 and 1896, of which H.M.S. Pinafore, The Pirates of Penzance and The Mikado are among the best known.

Gilbert, who wrote the libretti for these operas, created fanciful "topsy-turvy" worlds where each absurdity is taken to its logical conclusion; fairies rub elbows with British lords, flirting is a capital offence, gondoliers ascend to the monarchy, and pirates emerge as noblemen who have gone astray. Sullivan, six years Gilbert's junior, composed the music, contributing memorable melodies that could convey both humour and pathos.

Their operas have enjoyed broad and enduring international success and are still performed frequently throughout the English-speaking world. Gilbert and Sullivan introduced innovations in content and form that directly influenced the development of musical theatre through the 20th century. The operas have also influenced political discourse, literature, film and television and have been widely parodied and pastiched by humorists.

The producer Richard D'Oyly Carte brought Gilbert and Sullivan together and nurtured their collaboration. He built the Savoy Theatre in 1881 to present their joint works (which came to be known as the Savoy Operas) and founded the D'Oyly Carte Opera Company, which performed and promoted Gilbert and Sullivan's works for over a century.