Franz Paul Lachner (April 2, 1803 - January 20, 1890) was a German composer and conductor.

He was born in Rain am Lech to a musical family (his brothers Ignaz, Theodor and Vinzenz also became musicians). He studied music with Simon Sechter and Abbé Stadler . He conducted at the Kärntnertor Theater in Vienna before becoming a major figure in the musical life of Munich from the 1830s, conducting at the opera and various concerts and festivals. His career there came to a sudden end in 1864 after Richard Wagner's disciple Hans von Bülow took over Lachner's posts.

Lachner was a well-known and prolific composer in his day, though is not now considered a major composer. His work, influenced by Ludwig van Beethoven and Franz Schubert (who was a personal friend) is regarded as competent and craftsman-like, though relatively uninspired and unoriginal. Among his greatest successes were his opera Caterina Cornaro (1841), his Requiem and his seventh orchestral suite (1881).