Georg Matthias Monn (born Johann Georg Mann 9 April 1717, Vienna – 3 October 1750, Vienna) was an Austrian composer, organist and music teacher whose works were fashioned in the transition from the Baroque to Classical period in music.
Together with Georg Christoph Wagenseil and Josef Starzer, Monn formed the Viennese Pre-Classical movement ("Wiener Vorklassik"), whose composers are nowadays mostly known only by their names. However, his successful introduction of the secondary theme in the symphony was an important element for the First Viennese School (Haydn, Mozart, Beethoven and Schubert) that would come some fifty years later.