Thor Fossum (29 June 1916 - 21 August 1993) was a Norwegian politician for the Labour Party.
He was born in Bærum.
He was elected to the Norwegian Parliament from Akershus in 1961, and was re-elected on one occasion. He had previously served in the position of deputy representative in the period 1958 - 1961, but during this whole period he met as a regular representative since Halvard Manthey Lange had been appointed to the Cabinet.