Captain Scarlet vs. the Mysterons is a 1981 television film based on the 1960s British puppet TV series Captain Scarlet and the Mysterons created by Gerry and Sylvia Anderson. Produced by the New York office of the series' distributor, ITC Entertainment, the film is a compilation of the Captain Scarlet episodes "The Mysterons", "Winged Assassin", "Seek and Destroy" and "Attack on Cloudbase". It follows an earlier Captain Scarlet compilation, Revenge of the Mysterons from Mars.

Set in 2068, the original series depicts a "war of nerves" between Earth and the Mysterons: a race of Martians with the power to create functioning copies of destroyed people or objects and use them to carry out acts of aggression against humanity. Earth is defended by a military organisation called Spectrum, whose top agent, Captain Scarlet, was killed by the Mysterons and replaced by a reconstruction that subsequently broke free of their control. Scarlet's double has a self-healing power that enables him to recover from injuries that would be fatal to anyone else, making him Spectrum's best asset in its fight against the Mysterons.