Manifold: Origin (2001) is a science fiction novel by British author Stephen Baxter, the third instalment in the Manifold Trilogy. As with the other books, the protagonist Reid Malenfant is put through a scenario dealing with the Fermi paradox. Each novel is an alternative scenario rather than a chronological sequel, and does not occur in the same universe. Manifold: Origin explores primate evolution to create an explanation for our lack of contact with other intelligent species.

Manifold: Space is a science fiction book by British author Stephen Baxter, first published in the United Kingdom in 2000, then released in the United States in 2001. It is the second book of the Manifold series and examines another possible solution to the Fermi paradox. Although it is in no sense a sequel to the first book it contains a number of the same characters, notably protagonist Reid Malenfant, and similar artefacts. The Manifold series contains four books, Manifold: Time, Manifold: Space, Manifold: Origin, and Phase Space.