Girolamo Casati was an Italian composer and organist. He may have been the father (or some other relative) of Gasparo Casati. He became a Carmelite monk at an early age and held various church posts in Lombardy: as organist of Novara Cathedral in 1609 and of the cathedral at Romanengo, near Cremona, in 1625 and as maestro di cappella of Como Cathedral in 1635 and at S Maria del Carmine, Pavia, in 1654. He was one of a large number of north Italian church composers who published small-scale concertato motets, psalms and masses.