Fossum is a Norwegian surname. Notable people with the surname include:
Casey Fossum (born 1978), American baseball player Eric Fossum (born 1957), American professor and inventor Iver Fossum (born 1996), Norwegian association footballer Jon Fossum (1923–2007), Norwegian politician for the Conservative Party Karin Fossum (born 1954), Norwegian author Marita Fossum (born 1965), Norwegian author Michael E. Fossum (born 1957), American astronaut Per Fossum (1910–2004), Norwegian alpine skier who competed in the 1936 Winter Olympics Sindre Fossum Beyer (born 1977), Norwegian politician for the Labour Party Theresa Welch Fossum, American veterinary surgeon Thor Fossum (1916–1993), Norwegian politician Tryggve Fossum, Norwegian computer architect