Leif Selim Segerstam (/ˈleɪf/ LAYF, Swedish: [ˈlɛjf ˈsěːɡɛʂʈam]; born 2 March 1944) is a Finnish conductor, composer, violinist, violist and pianist, especially known for writing 344 symphonies as of April 2021, along with other works in his extensive oeuvre.
Segerstam has conducted a variety of orchestras since 1963; mostly American, Australian and European. He is widely known through his recordings, which include the complete symphonies of Blomdahl, Brahms, Mahler, Nielsen, and Sibelius, as well as many works by contemporary composers, such as the American composers John Corigliano and Christopher Rouse, the Finnish composer Einojuhani Rautavaara, Swedish composer Allan Pettersson and the Russian composers Alfred Schnittke and Alexander Scriabin.
His contributions to the Finnish music scene, and his vibrant personality, have contributed to his fame. He is well known for his high energy during performances, contributing to the musicality of the orchestra as a whole.