Friedrich Wilhelm Jähns (German: [jɛːns]; 2 January 1809 – 8 August 1888) was a German music scholar, voice teacher, and composer. He is best known for his thematic catalog of the works of Carl Maria von Weber. Jähns was born and died in Berlin. His grave is preserved in the Protestant Friedhof I der Jerusalems- und Neuen Kirchengemeinde (Cemetery No. I of the congregations of Jerusalem's Church and New Church) in Berlin-Kreuzberg, south of Hallesches Tor.