A bizarre alien lifeform that arrived on Earth in a comet, Hedorah quickly grew to gigantic size by feeding on humanity's pollution. Beginning as a huge tadpole-like creature, Hedorah transformed into a terrestrial form and came ashore in Japan, where it battled Godzilla. Continuing to grow and evolve, Hedorah took on an airborne form capable of spreading clouds of toxic mist and finally a colossal bipedal form that dwarfed even Godzilla. Hedorah was finally destroyed by a combination of Godzilla's efforts and a device constructed by humanity, but the threat of rampant pollution giving rise to another Hedorah remained. Hedorah's next onscreen appearance came in Godzilla Final Wars, where it was a pawn of the Xiliens in their invasion of Earth. Hedorah was unleashed along with Ebirah to battle Godzilla in Tokyo Bay, but Godzilla made short work of both monsters.