Kalevi Ensio Aho (born 9 March 1949) is a Finnish composer. Known principally as a composer of large-scale works, as of 2024 Aho has composed eighteen symphonies, forty-two concertos, five operas and several vocal works. His chamber music includes several quintets, quartets, sonatas and solo works. He first came to fame with his first symphony (1969) and second string quartet (1970). His works of this time showed such neo-classical traits as a preoccupation with counterpoint (particularly fugues), and stylized renderings of older forms, such as the waltz. In the following decade he wrote in modernist and post-modernist styles. His use of irony and juxtaposition of contrasting moods and musical styles and genres has been compared to Gustav Mahler and Alfred Schnittke.