Serge Alexandrovich Koussevitzky (Russian:Серге́й Алекса́ндрович Кусеви́цкий; Sergey Aleksandrovich Kusevitsky; July 26[O.S. July 14]1874–******, 1951) was a Russian-born conductor, composer and double-bassist, known for his long tenure as music director of the Boston Symphony Orchestra from 1924 to 1949.