Mysteron

The Mysterons were a race from the planet Mars who waged a war of vengeance against humanity during the mid-to-late 21st century in retaliation for Captain Black of the SSEC's Mars Expedition firing upon the Mysteron City "in a moment a panic". The security organisation Spectrum, Black's former employer, soon emerged as Earth's main defence.

Little was known about the Mysterons' true nature, with the "latest information" indicating they were computerised versions of non-corporeal beings that abandoned Mars before humans arrived there. (COMIC: ) Using their retrometabolic ray they had the ability to enact a process termed Mysteronisation, affording the Mysterons the power to reconstruct indestructible replicas of objects or persons and often used to create physical instruments on Earth with which to carry out their repeated threats. (COMIC: et al.)

Beginning of the Mysteron War
In either June of 2067 (PROSE: Capt. Black Mars Expedition Lost!) or 2087, (PROSE: Rogues Gallery) Captain Black commanded a Zero X expedition to Mars in order to investigate the "strange radio signals" (PROSE: Capt. Black Mars Expedition Lost!,  'Jinx Ship' Blasts Off For Mars) received from the Rock Snake Hills area over the previous year. (PROSE: Capt. Black Mars Expedition Lost!)

Upon reaching the planet, Black proceeded to investigate the Mysteron City. In a moment of panic, he opened fire on the city, (PROSE: Rogues Gallery) thus beginning the Mysteron War. (PROSE: 'Jinx Ship' Blasts Off For Mars, Rogues Gallery) On 2 September 2067, TV 21 stated that Glenn Field had reported the loss of Black's expedition, with the publication speculating that "whatever was causing the signals" had "accounted" for Black and his crew. (PROSE: Capt. Black Mars Expedition Lost!)

Zero X, with Black aboard, unexpectedly returned to Earth on 23 September 2067. On its approach to Glenn Field, the craft collided with the small passenger jet TGW 197 K which was carrying the TV Century 21 reporters Pete Tracker and Lens Sharpe. The commotion and confusion this incident caused allowed Black to exit Zero X and leave Glenn Field in a car, vanishing without trace thereafter. (COMIC: SPECTRUM, PROSE: SPECTRUM is Green) Doctor Giardeles would later offer the opinion that Captain Black had in fact been killed by the Mysterons on Mars, serving only as an indestructible mouthpiece for them after that point. (PROSE: Rogues Gallery)

The Mysterons' "first brush" with Spectrum's Captain Scarlet occurred when he was killed in a motor accident and subsequently brought back to life (PROSE: Captain Scarlet and the Mysterons) through Mysteronisation. (PROSE: Scarlet Kidnapped!) Under their control, Scarlet attempted to assassinate the World President. (PROSE: Captain Scarlet and the Mysterons) This led to a battle with Spectrum forces (PROSE: Marineville Ablaze) atop London Car-Vue (PROSE: Scarlet Kidnapped!, Marineville Ablaze) during which Scarlet was fatally shot by Captain Blue, (COMIC: ) causing him to fall eight hundred feet. (PROSE: Captain Scarlet and the Mysterons, COMIC: ) An examination by Doctor Fawn revealed the fall had broken the Mysteron spell, bringing Scarlet back under Spectrum's control while allowing him to retain his indestructibility. (COMIC: We Will Destroy Unity City)

Threats to destroy
In 2067, the Mysterons plotted to destroy London. Their plan involved a H-bomb but it was foiled when Captain Scarlet brought the bomb in an SPV to a location off the coast of Land's End, where it harmlessly exploded.

Soon afterwards, the Mysterons announced their threat to destroy Unity City. Initially, they plotted to use the Spectrum headquarters of Cloudbase to carry out their aims. Captain Black helped to facilitate this by shooting down an Angel aircraft which had been despatched to Unity City in response to the threat. The craft was Mysteronised and began to head back to Cloudbase but its progress was permanently halted when Captain Scarlet, travelling to Unity City in a jet of his own, detected the Mysteron influence at play and rammed the Angel mid-air, obliterating both craft. Black persisted in his attempts to capture Cloudbase, being ordered by the Mysterons to spray the surrounding clouds with D17 poison gas after they noted that Cloudbase was moving position. The gas knocked the entirety of Cloudbase's personnel save one unconscious but Black's efforts to alter its course was once again foiled by Captain Scarlet, who had been placed in a purified atmosphere to recover from his earlier crash.

Following an encounter with a band of Fijian fishermen, Captain Black found himself on a beach as a prisoner of Scarlet and Angels Destiny, Harmony and Melody. The ever-watchful Mysterons activated their agent's audio-field which produced a high frequency sound that incapacitated everyone else, allowing Black take Scarlet and leave without resistance. He was then aided by a Mysteron in Marineville and a Mysteron at the Southern Californian Research Station to blast off in the Alpha Centauri Space Probe. Black achieved a course change for Mars, now intent on returning Scarlet to Mysteron control, but the Probe was pursued and destroyed by a squad of World Space Patrol ships. Witnessing the destruction of the rocket, the Mysterons activated the retrometabolic ray to afford Black an escape route, which he took, the crew of Fireball XL2 being too preoccupied with treating the barely-alive Captain Scarlet to follow the reconstrutcted rocket. (COMIC: )

Behind the scenes

 * The Mysterons were the titular antagonists of the Gerry and Sylvia Anderson-created television programme Captain Scarlet and the Mysterons. The series had many crossovers with the Doctor Who universe through prose and comic form within the pages of TV Century 21.
 * The Mysterons were pastiched in the Doctor Who novel The Indestructible Man, which paid homage to several of the Andersons' prior works. Elements of the Mysterons were combined with those of the unnamed aliens from to create the Myloki.