Mendelssohn, MEHN duhl suhn, Felix (1809-1847), was a German composer who was widely known and respected in his time. Mendelssohn also gained fame as a conductor and pianist. He also played a significant role in reviving interest in the music of German composer Johann Sebastian Bach. Mendelssohn held high standards of excellence in composition, performance, and musical training that have had an enormous effect on musicians in the 1800's and 1900's.