Double, Double is a science fiction novel by John Brunner, first published in the United States as an original paperback by Ballantine Books in 1969 and reprinted in 1979 as a Del Rey paperback.

A hardcover edition was released in the British market in 1971 by Sidgwick & Jackson.

[1] Bruno and his band The Hermetic Tradition visit the North Kent coast where they plan to hold an open-air cliff-top concert.

Events take an unusual turn when the band meet a fish capable of eating and doubling the things it finds.

[2] Spider Robinson dismissed the novel, saying "there just ain't all that much right with it.