Hedorah

Hedorah is an alien that feeds on pollution.

History
Hedorah was a microscopic alien that landed on Earth and began feeding on its pollution, growing bigger and stronger. Godzilla confronted him and Hedorah was easily defeated due to still being young. Unfortunately, Hedorah still grew bigger due to the pollution and transformed into a flying form. Hedorah flew over several cities and sprayed sulfuric acid, killing thousands of humans instantly. Godzilla had one final battle with Hedorah on Mt. Fuji, but even Godzilla was overwhelmed by Hedorah's strength, losing an eye and having his hand burned to the bone. The humans constructed electrodes to dry out Hedorah's body, but a fuse was blown. Godzilla re-energized them and electrocuted Hedorah, drying out his body and defeating him.

Unfortunately, Hedorah would rise again, and this time he plagued Godzilla Island. He crashed to Earth in a meteor and Xilien Zaguresu released him. He sprayed poisonous gas over the island, causing acid rain to fall, subduing the monsters, including Godzilla. However, Torema was sent to stop the acid rain. When Zaguresu tried to stop her, she came too close to the cloud and the ship disperses the cloud. Hedorah leaves and heads to Mothra's cave. Most of the monsters are still weak from the acid rain. Mothra flies out to protect her offspring from Hedorah, but is gassed by Hedorah and shot by his eye laser, knocking her unconscious. The Mothra Larvae crawls out to see Mothra down, and Hedorah passes Mothra to kill the baby. However, a recovered Godzilla blasts Hedorah with his atomic ray. This does little and Hedorah easily subdues Godzilla before chasing after the Mothra Larvae. However, the adult uses her remaining strength to grab Hedorah and fly him to a volcano that she drops him in, but the resulting explosion kills Mothra, much to Torema's horror. Unfortunately, Hedorah survives and climbs out of the volcano. Mothra Larvae has gone into a cocoon, and Hedorah approaches it. Suddenl, he is knocked down by Godzilla's ray, The two grapple with each other as Mothra Larvae hatches into an adult. Godzilla and Mothra Larvae use their beams to dry out Hedorah, and Godzilla crushes what is left. The spirit of Mothra then comes and Torema and the new Mothra say goodbye.

However, this was not the last time Hedorah was seen. Hedorah was stomping through Tokyo Harbor at one point during an Xilien invasion, though it is unknown if he was apart of it. Godzilla blasted him and a giant lobster Ebirah out of Tokyo Harbor, with Ebirah piercing Hedorah's eye. Godzilla destroyed them both with a blast from his ray.