The Eaters are the main villains from the 1993 unreleased Arcade game Chimera Beast.
They are an enigmatic mutant species that naturally emerged on a planet similar to Earth. These monstrosities only purpose is to consume other lifeforms, assimilating their DNA to continually evolve, acquiring the characteristics of their prey. All lifeforms other than themselves are merely foods to these creatures.
The player controls one such Eater (two Eaters if including player two), starting as a microorganism preying on bacteria and other microbes. Each stage has the Eater climbing one step further on the food chain and evolution, taking on fish, birds, reptiles and mammals. By the penultimate stage, the Eater attacks mankind, being gigantic enough to destroy whole buildings. At the end of the stage, it destroys a nuclear power plant, thus causing a nuclear cataclysm on the hapless planet. The final stage has the Eater(s) preying on other Eaters while the nuclear explosion destroys the planet.
After destroying a huge human space shuttle containing humans who were attempting to flee the planet, the players' Eaters are to have one final duel of cannibalism against another giant-sized Eater.
Now, there are two different types of endings: if the player Eater(s) win(s), all life on the planet is extinguished and the planet's ecosystem devastated is beyond recovery, so the Eater(s) continues traveling the universe, searching for more victims and destroying more planets, until one day when it will finally reach Earth. But if the player Eater(s) either loses to the boss Eater or fails to kill the boss Eater in time, the surviving Eaters cannibalize each other and the planet's damaged ecosystem will gradually heal itself. Most cases the first ending would be considered a bad ending and the latter ending would be considered good ending. Not so with Chimera Beast, with rapacious predators that keep on eating until all lifeform is extinguished being protagonists first ending is considered legitimate and the second is actually bad.