Gustav Fredrik Lange (February 22, 1861 – February 11, 1939) was a Norwegian violinist, violin teacher, theory teacher, and composer. During his time, he was considered one of Norway's best in his field.

Lange was born in Halden.^[1] He was the second concertmaster of the Oslo Philharmonic from its beginning in 1919, and for a time he served as first concertmaster at the Christiania Theatre and National Theatre.^[1] With Ole Olsen and Edvard Grieg, he created music for Henrik Ibsen's comedy The League of Youth (premiere at the Swedish Theatre, 1901). Like Ole Olsen, Lange was a Freemason and worked as a conductor and arranger for the Freemasons Orchestra (1921–1936). In Halden he was a member of a chamber quartet together with Oscar Borg (his violin teacher in his youth),^[1] Markus Boberg, and the cellist Dupery Hamilton.^[2]

Together with Peter Brynie Lindeman, Lange edited the periodical Orkestertidende—blad for musikere og musikervenner (The Orchestra Times: A Paper for Musicians and Their Friends; 1892–1894). Lange was a cofounder of the Oslo Music Teachers Association, the Norwegian Music Teachers' National Federation, and the National Federation of Norwegian Musical Artists (Norwegian: Norsk Tonekunstnersamfund). He also taught violin, theory, and harmony at the Oslo Conservatory of Music (1889–1937).

Lange died in Oslo.^[1]