Alastair G. W. (Graham Walter) Cameron (21 June 1925 – 3 October 2005) was an American-Canadian astrophysicist and space scientist who was an eminent staff member of the Astronomy department of Harvard University. He was one of the founders of the field of nuclear astrophysics, advanced the theory that the Moon was created by the giant impact of a Mars-sized object with the early Earth, and was an early adopter of computer technology in astrophysics.