Józef Antoni Franciszek Elsner (sometimes Józef Ksawery Elsner; baptismal name, Joseph Anton Franz Elsner; 1 June 1769 – 18 April 1854) was a 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.
He composed many symphonic, chamber, solo, and vocal-instrumental (some 120 of them, religious) works, and 38 operas. He is perhaps best known as the principal piano teacher of the young Frédéric Chopin.
Józef Elsner was born in Grottkau, Herzogtum Neisse (Duchy of Nysa), near Breslau, Kingdom of Prussia, on 1 June 1769, to Silesian Catholic parents Franz Xaver Elsner. His mother was from the famous Matzke family of Glatz, which had intensive contacts with Czech culture in Bohemia. Józef Elsner was initially educated for the priesthood at Breslau's Dominican monastery school, St. Matthew's Gymnasium, and a local Jesuit college, but chose the music field. In 1832–37 he would compose nineteen religious pieces for Breslau Cathedral.
After completing his studies at Breslau and being a violinist at Brünn, in 1792 he became 2nd Kapellmeister at the German Opera in Austrian-ruled Lemberg. There in 1796 he married Klara Abt, who died a year later. In 1799, with Wojciech Bogusławski, he went to New East Prussia (Prussian-ruled Poland) and became the principal conductor, first at the German Theatre, then at the Polish National Theatre in Warsaw.
Elsner traveled to Paris, Dresden and Posen (Poznań), where he met E.T.A. Hoffmann. Together they founded the Musikressource in 1805. In 1802 he had married a second wife, Karolina Drozdowska. Due to complaints that he preferred Germans, he resigned from theater work.
During his decades in Warsaw, Elsner's name and family life gradually polonized. Elsner's ethnicity should not be evaluated in terms of 19th- and 20th-century national identity, as he continued to refer to himself primarily as a Silesian.
Elsner taught the composers Ignacy Feliks Dobrzyński and Frédéric Chopin. There are also indications that he privately tutored piano composer and virtuoso Maria Szymanowska. Chopin dedicated to Elsner his Piano Sonata No. 1 in C minor, Op. 4 (1828), composed while he was studying with Elsner. As Chopin's only piano teacher in 1823-29, Elsner taught him music theory and composition; Elsner diaried of Chopin: "Chopin, Fryderyk, third-year student, amazing capabilities, musical genius."
On 18 April 1854, Elsner died at his estate named for himself, Elsnerów, which now lies within the Warsaw city limits.
Elsner's compositions included
- operas Leszek Biały (Leszek the White) and Król Łokietek (about Władysław I the Elbow-high)
- oratorio, Męka Pana Naszego Jezusa Chrystusa (The Passion of Our Lord Jesus Christ)
- eight symphonies
- polonaises, waltzes, marches
- Mass in B-flat major and Mass in F major
- Nieszpory do NMP (Vespers for the Most Sacred Virgin Mary).
He also wrote Sumariusz moich utworów muzycznych (Summary of My Musical Works, published 1957).
- "Neue Deutsche Biographie (NDB) (in German) (Berlin: Duncker & Humblo) 4, 1959: 466–467",
- Array von Dommer (1877), "Elsner, Joseph", Allgemeine Deutsche Biographie (ADB) (in German) 6, Leipzig: Duncker & Humblot, pp. 70–71
- Martina Homma: Nationale Musik und nationale Musikwissenschaft. Der Fall Joseph Elsner. In: Deutsch-polnische Ansichten zur Literatur und Kultur. Wiesbaden 1995, S. 104–116 
- "Elsner, Józef," Encyklopedia Polski, Kraków, Wydawnictwo Ryszard Kluszczyński, 1996, p. 154.