Johann(es) Simon Mayr (also spelled Majer, Mayer, Maier), also known in Italian as Giovanni Simone Mayr or Simone Mayr (14 June 1763 – 2 December 1845), was a German composer. He was an early inspiration to Rossini. He was born in Mendorf near Altmannstein, Landkreis Eichstätt, Bavaria, and studied theology at the University of Ingolstadt, continuing his studies in Italy from 1787. He was closely associated with the Illuminati of Adam Weishaupt while a student in Ingolstadt, and the ideals of the French Enlightenment were a strong influence on his philosophy as a musician as corroborated by his famed Zibaldone or "Notebooks" compiled toward the end of his career.