Nils Mathisen (born 24 January 1959) is a Norwegian Jazz musician (Keyboards, Violin, guitar and bass) and Composer, known from significant efforts within cabaret and musicals. Mathisen has released two solo albums, and contributed to releases by Jan Werner, Elisabeth Andreassen, Elg and Arild Nyquist. He is the brother of Jazz musicians Per Mathisen (bass), Hans Mathisen (guitar) and Ole Mathisen (saxophone and clarinet).