For other uses of The Mysterons see The Mysterons (Disambiguation).
The Mysterons is the first produced, and broadcast, episode of the British television series Captain Scarlet and the Mysterons.
Spectrum's Captain Black makes a fatal error on Mars which starts a war between Earth and Mars' inhabitants known as the Mysterons. The Mysterons threaten to destroy all life on Earth and declare their first target to be the World President James T. Younger. Captain Scarlet is caught in the crossfire, but after his experience, he becomes virtually indestructible...
- Main article: The Mysterons (episode)/Storyline
- Harmony Angel was voiced by Liz Morgan in this episode and 4 others; she was voiced by Lian Shin in The Launching.
- In the original shot of the opening scene the puppets for the Medical Students in Operation Time were used in place of Lieutenant Dean & Navigator Conway.
- When inside the Spectrum Passenger Jet, Captain Scarlet and the World President are both wearing pilot glasses. However, some exterior shots show them without them.