John R. Gribbin (born 1946) is a British science writer, an astrophysicist, and a visiting fellow in astronomy at the University of Sussex. The topical range of his prolific writings include quantum physics, biographies of famous scientists, human evolution, the origins of the universe, climate change and global warming. His writings often speculate on what some critics consider science fiction.

John Gribbin graduated with his bachelor's degree in physics from the University of Sussex in 1966. Gribbin then earned his master of science (M.Sc.) degree in astronomy in 1967, also from the Univ. of Sussex, and he earned his Ph.D. in astrophysics from the University of Cambridge (1971).

In 1968, Gribbin worked as one of Fred Hoyle's research students at the Institute of Theoretical Astronomy, and wrote a number of stories for New Scientist about the Institute's research and speculation into what were eventually discovered to be pulsars.

In 1974, Gribbin published, along with Stephen Plagemann, a book titled The Jupiter Effect, that predicted that the alignment of the planets in quadrant on one side of the Sun on March 10, 1982 would cause gravitational effects that would trigger earthquakes in the San Andreas fault, wiping out Los Angeles and its suburbs. Gribbin repudiated The Jupiter Effect in the July 17, 1980, issue of New Scientist magazine in which he stated that he had been "too clever by half".