Falstaff is an opera in three acts by Giuseppe Verdi. The libretto was adapted by Arrigo Boito from Shakespeare's The Merry Wives of Windsor and scenes from Henry IV, parts 1 and 2. The work, described by its creators as a commedia lirica, premiered on 9 February 1893 at La Scala, Milan. Falstaff, written when Verdi was approaching the age of eighty, was the last of his twenty-eight operas, and was only his second comedy. It was his third work based on a Shakespeare play, following Macbeth and Otello.

Although the prospect of a new opera from Verdi aroused immense interest in Italy and round the world, the opera did not prove to be as popular as earlier works in the composer's canon. After the initial performances in Italy, other European countries and the US the work was neglected until the conductor Arturo Toscanini insisted on its revival at La Scala and the Metropolitan Opera in New York. Some felt that the piece suffered from a lack of the full-blooded melodies of the best of Verdi's previous operas, a view strongly contradicted by Toscanini. Conductors of the generation after Toscanini to champion the work included Herbert von Karajan, Georg Solti and Leonard Bernstein. The work is now part of the regular operatic repertory.

Verdi made numerous changes to the music after the first performance and editors have found difficulty in agreeing on a definitive score. The work was first recorded in 1932 and has received many studio recordings and live tapings subsequently. Among those most closely associated with the title since its creator, Victor Maurel, have been Mariano Stabile, Giuseppe Valdengo, Tito Gobbi, Geraint Evans and Bryn Terfel.