Many members of the CO player community have long expressed a desire for more content of one kind or another in the game. However, most of us have come to accept that the resources the current game developers have to work with are limited, restricting both the amount and kind of content they can produce. However, while perusing Champions Beyond, the PnP game book which details the extraterrestrial side of the official Champions setting, it occurred to me that one of the alien races it describes has great potential to produce a significant event, even a comic series, requiring very little beyond what already exists in the game.
The Eauhiaomeaaeiu (that name is an approximation of the species' designation for itself, an electric-like hum unpronounceable by most beings) are hive-mind entities, forming "clouds" made up of motes of psionic energy. An exploitative parasitic species, Eauhiaomeaaeiu swarm-clouds drift through space looking for planets inhabited by sapient beings. When a swarm finds such a world, it infects one of the inhabitants, taking control of its mind and body. The swarm then "breeds" by spawning motes to infect other people. Eventually the Eauhiaomeaaeiu take over the planet's entire population. They strip the world bare of all its exploitable resources, ultimately leaving it unable to sustain their host bodies. The Eauhiaomeaaeiu swarms then abandon that planet and seek others, leaving their former hosts to starve and die.
The Eauhiaomeaaeiu takeover process isn't infallible, though. The long journey through space, and exposure to cosmic phenomena, can leave a swarm weakened or damaged. One such swarm came to Earth and tried to possess a human; but her strong will and latent psychic abilities, awakened by contact with the swarm, ultimately overcame and absorbed the weak Eauhiaomeaaeiu, producing a composite being with formidable mental powers and a personality fusing her human and alien mentalities. She has since become known as the supervillain Esper (detailed in Champions Villains Vol. 3: Solo Villains).
There are other swarms in the galaxy, though, and it would not be at all unreasonable for a second one to reach Earth, and to be more successful in its takeover attempt -- the "invasion of the body-snatchers" scenario. As a result, any existing characters in the game could become enemies bent on taking over the planet: mobs made up of ordinary people, existing factions in the game, police, UNTIL agents, supervillains, even major NPC allies and superheroes. The story could feature plenty of "who do you trust?" paranoia as those not infected seek a way to drive out the possessing Eauhiaomeaaeiu; but also bring to bear any desired level of physical opposition to heroes looking to fight them. The precedent of Esper also suggests the event could, if desired, spawn newly created supervillains, NPC heroes, or even become the origin for PC heroes.