Ludwig Wenzel Lachnith (Prague, July 7, 1746 – Paris, October 3, 1820) was a Bohemian horn player and versatile composer influenced by Joseph Haydn and Ignaz Pleyel. Today he is chiefly remembered because of his adaptions of operas by Wolfgang Amadeus Mozart. The French composer and writer Hector Berlioz immortalized him in a diatribe in his autobiography.