Józef Antoni Franciszek Elsner (sometimes Józef Ksawery Elsner; baptismal name, Joseph Anton Franz Elsner; 1 June 1769 – 18 April 1854) was a Polish composer, music teacher, and music theoretician, active mainly in Warsaw. He was one of the first composers in Poland to weave elements of folk music into his works.

Elsner composed many symphonic, chamber, solo, and vocal-instrumental works, and works for the stage, including over 100 religious works (masses, offertories, oratorios, cantatas), eight symphonies, three concertos, three ballets, and thirty-eight operas. He is perhaps best known as the principal composition teacher of the young composer Frédéric Chopin.