Leif Fritjof Halvorsen (July 26, 1887 – December 28, 1959) was a Norwegian violinist, conductor, and composer.

Leif Halvorsen was a highly sought-after violin teacher, and he composed violin pieces, a string quartet, two cantatas, piano pieces, and music for poems by Heinrich Heine and Vilhelm Krag.

In 2009, the film with its music by Leif Halvorsen was shown at the Hamsun jubilee in Hamarøy Municipality.

A DVD with the movie has been released, with the Norwegian Radio Orchestra playing Leif Halvorsen's score.

[7] The composer Fartein Valen dedicated his Sonata for Violin and Piano (Opus 3), written between 1912 and 1919, to Halvorsen.