Xavier Henry Napoleón Leroux (October 11, 1863 in Velletri, Italy – February 2, 1919 in Paris) was a French composer.
Leroux was the son of a military bandleader. He studied at the Paris Conservatory under Jules Massenet and Théodore Dubois, and won the Prix de Rome in 1885 with the cantata Endymion. From 1896 he taught harmony there. Notable students include composer Marc Delmas.
Leroux composed several orchestral and choral works, songs, and piano pieces, but he was primarily known for his operas.
- Evangéline, libretto by Louis de Gramont, 1895
- Astarté, libretto by Louis de Gramont, 1901
- La reine Fiammette, 1903
- Vénus et Adonis, libretto by Louis de Gramont, 1905
- William Ratcliff, libretto by Louis de Gramont after Heinrich Heine, 1906
- Le chemineau, 1907
- Théodora, 1907
- Le carillonneur, 1913
- La fille de Figaro, 1914
- Les cadeaux de noël, 1915
- 1814, 1918
- Nausithoé, 1920
- La plus forte, 1924
- L'ingénu, 1931
- Don Randel, The Harvard Biographical Dictionary of Music. Harvard, 1996, p. 499.