The Reign of Terror is the eighth serial in the British science fiction television series Doctor Who, which was first broadcast on BBC1 in six weekly parts from 8 August to 12 September 1964. It was written by Dennis Spooner and directed by Henric Hirsch. In the serial, the First Doctor, his granddaughter Susan, and teachers Ian Chesterton and Barbara Wright arrive in France during the period of the French Revolution known as the Reign of Terror, where they become involved with prisoners and English spies.

Doctor Who is a British science fiction television series broadcast by the BBC since 1963. The series, created by Sydney Newman, C. E. Webber and Donald Wilson, depicts the adventures of an extraterrestrial being called the Doctor, part of a humanoid species called Time Lords. The Doctor travels in the universe and in time using a time travelling spaceship called the TARDIS, which externally appears as a British police box. While travelling, the Doctor works to save lives and liberate oppressed peoples by combating foes. The Doctor often travels with companions.