2001: A Space Odyssey is a 1968 science fiction novel by British writer Arthur C. Clarke. It was developed concurrently with Stanley Kubrick's film version and published after the release of the film. Clarke and Kubrick worked on the book together, but eventually only Clarke ended up as the official author. The story is based in part on various short stories by Clarke, including "The Sentinel" (written in 1948 for a BBC competition, but first published in 1951 under the title "Sentinel of Eternity"). By 1992, the novel had sold three million copies worldwide. An elaboration of Clarke and Kubrick's collaborative work on this project was made in the 1972 book The Lost Worlds of 2001.
The first part of the novel, in which aliens influence the primitive ancestors of humans, is similar to the plot of Clarke's 1953 short story "Encounter in the Dawn".