Hedorah is an alien pollution kaiju who first appeared in the 1971 Toho Godzilla film Godzilla vs. Hedorah. 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.