The Keys of Marinus is the fifth serial in the British science fiction television series Doctor Who, which was first broadcast on BBC TV/BBC1 in six weekly parts from 11 April to 16 May 1964. Written by Terry Nation and directed by John Gorrie, the serial takes on a "mini-adventures" format, in which the First Doctor, his granddaughter Susan Foreman, and her teachers Ian Chesterton, and Barbara Wright search for four keys to restore the Conscience of Marinus, a computer which maintains law and order. The group travel to two cities, a jungle, and an icy wasteland in search of the keys.

Terence Joseph Nation was a Welsh screenwriter and novelist. Especially known for his work in British television science fiction, he created the Daleks and Davros for Doctor Who, as well as the series Survivors and Blake's 7.