Abadon was a Marvel Comics supervillain and opponent of the Shadow Riders.
Abadon originally existed in its own universe, where it was an entity that an elemental force of nature. However, the demon lord Mephisto wrenched Abadon from its realm, seeking to control its power for his own uses. That act reshaped Abadon into an individual entity. Weakened by the trauma and stunned by its newfound consciousness, Abadon was nearly enslaved by Mephisto. However, it managed to use its remaining energies to escape to earth and cloak itself in human form. This process caused Abadon to forget its true nature and past, leaving it as an amnesiac man in London, England. This man was soon captured by the criminal organization known as Mys-Tech, who sensed his power and wished to control it.
The man, named Matthew Ryan by Mys-Tech, was brought before Porlock, one of the Techno-Wizards that run the organization. Porlock had Ryan subjected to testing to explore his powers. Porlock discovered a portion of Abadon's true nature, and used post-hypnotic suggestion to both control him, and allow him to regain his memories and power when Porlock mentioned his true name in the future. Porlock then set Ryan up to appear as a mutant human being tortured by Mys-Tech. Ryan's energy levels were detected by others who sought to save him, including the mutant known as Cable, and the team known as the Shadow Riders, who oppose the activities of Mys-Tech.
The Shadow Riders succeeded in freeing Ryan, and their leader, Vorin convinced him to use his energies to help open a portal to Vorin's homeworld to fight off Mys-Tech oppression there. While Vorin and the Shadow Riders made preparations for the journey, another Shadow Rider, a woman known as Roadie, befriended Ryan, easing his nightmares and explaining the team's goals to him. Upon arriving on Vorin's homeworld, now known as Arena World, the Shadow Riders were ambushed by a powerful group known as the Slaughterhouse Six. In the midst of the battle, Porlock appeared and said the word "Abadon," causing the expected transformation, and Abadon used his powers to capture both Cable and the Shadow Riders.
The Shadow Rider known as Stranger enabled himself and the others to escape, and when Porlock reprimanded Abadon, his control began to break down, and Abadon attacked and quickly overpowered him. Roadie re-established contact with the man she knew as Ryan, but an attack by other team members ruined any success of a peaceful ending. The Shadow Riders opened a portal to Earth, and closed it on Abadon when he attempted to pass through it.