Iris is an opera in three acts by Pietro Mascagni to an original Italian libretto by Luigi Illica. It premiered on 22 November 1898 at the Teatro Costanzi in Rome. The story is set in Japan during legendary times.

In common with all of Mascagni's full-length operas, Iris is now rarely performed, even in Italy, although along with L'Amico Fritz it remains one of the composer's more performed operas. Two of the opera's most memorable numbers are the tenor's serenade ("Apri la tua finestra") and the Hymn to the Sun ("Inno al Sole").

The so-called "aria della piovra" ("Octopus aria"), "Un dì, ero piccina", where Iris describes a screen she had seen in a Buddhist temple when she was a child, depicting an octopus coiling with its tentacles around a young woman, may have been inspired by the print "The Dream of the Fisherman's Wife" (1814) by the Japanese artist Hokusai.