John Olsen was premier of South Australia, 1996–2001.
John Olsen may also refer to:
- John W. Olsen (born 1955), American archaeologist
- John Olsen (Australian artist) (1928–2023), Australian landscape and abstract artist
- John Olsen (Danish artist) (born 1938), Danish artist specializing in sculpture
- John Olsen (filmmaker) (1888–1959), Danish producer, screenwriter and studio owner
- John Olsen (footballer)
- Jack Olsen (1925–2002), American journalist and author