Johann Philipp Kirnberger (also Kernberg; 24 April 1721, Saalfeld – 27 July 1783, Berlin) was a musician, composer (primarily of fugues), and music theorist. Possibly, though not verified, he was a pupil of Johann Sebastian Bach, visiting Leipzig in 1741. Between 1741 and 1751 Kirnberger lived and worked in Poland for powerful magnates including Lubomirski, Poninski, and Rzewuski before ending up at the Benedictine Cloister in Lvov (then part of Poland). He became a violinist at the court of Frederick II of Prussia in 1751. He was the music director to the Prussian Princess Anna Amalia from 1758 until his death. Kirnberger greatly admired J.S. Bach, and sought to secure the publication of all of Bach's chorale settings, which finally appeared after Kirnberger's death; see Kirnberger chorale preludes (BWV 690–713). Many of Bach's manuscripts have been preserved in Kirnberger's library (the "Kirnberger collection").
He is known today primarily for his theoretical work Die Kunst des reinen Satzes in der Musik (The Art of Strict Composition in Music, 1774, 1779). The well-tempered tuning systems known as "Kirnberger II" and "Kirnberger III" are associated with his name (see Kirnberger temperament), as is a rational version of equal temperament (see schisma).