Pietro Antonio Stefano Mascagni (; 7 December 1863 – 2 August 1945) was an Italian composer most noted for his operas. His 1890 masterpiece ''Cavalleria rusticana'' caused one of the greatest sensations in opera history and single-handedly ushered in the ''Verismo'' movement in Italian dramatic music. Some critics held that Mascagni, like Leoncavallo, was a "one-opera man" who could never repeat his first success, but ''L'amico Fritz'' and ''Iris'' have remained in the repertoire in Europe since their premieres. Mascagni said that at one point, ''Iris'' was performed in Italy more often than ''Cavalleria'' (cf. Stivender).
Mascagni wrote fifteen operas, an operetta, several orchestral and vocal works, as well as songs and piano music. He enjoyed immense success during his lifetime, both as a composer and conductor of his own and other people's music. He created a variety of styles in his operas: a Sicilian passion and warmth of ''Cavalleria'', the exotic flavor of ''Iris'', the idylls of ''L'amico Fritz'' and ''Lodoletta'', the Gallic chiaroscuro of ''Isabeau'', the steely, Veristic power of ''Il piccolo Marat'', the over-ripe post-romanticism of the lush ''Parisina,'' which demonstrate a versatility.