Godzilla (1954)

Gojira is the original Godzilla. He was an ordinary dinosaur called the Godzillasaurus that was mutated by nuclear radiation, causing him to grow to enormous proportions and become a radioactive monster. He serves as the main antagonist in Gojira and Godzilla Mothra and King Ghidorah: Giant Monsters All-Out Attack.

History
A Japanese fishing boat is destroyed by a flash of light near Odo Island, and another ship sent to investigate meets the same fate. The elder at Odo Island blames their poor fishing on Gojira, who they would sacrifice girls to. They perform a ceremony to keep the monster away, but as they sleep, Gojira rises and attacks, killing many.

Archeologist Kyohei Yamane arrives at the island and comes across giant, radioactive footprints. An alarm is sounded, and the natives arm themselves and are attacked by Gojira. After a fight, Gojira leaves back to the ocean.

After Gojira's presence is released to the public, ships are sent to kill him, but they fail and Gojira appears again, causing panic. Officials appeal for Yamane for some way to kill the monster, but Yamane wants to keep Gojira alive to study him.

During the night, Gojira rises from Tokyo Bay and attacks the city. He leaves quickly, but he kills a large number of people. The army constructs an electrical tower to keep Gojira away. However, Gojira breaks through the tower and massacres the city. This results in the city being in ruins, with hospitals overflowing with victims, several having radiation burns. Yamane's daughter Emiko reveals to Hideto Ogata that Daisuke Serizawa has a machine called the Oxygen Destroyer that disintegrates oxygen atoms and orgasms, killing the life form. Serizawa refuses to use the weapon, fearing the military will misuse it. However, when seeing the devastation Gojira caused, he agrees to use it. He burns all his research and eventually uses the Oxygen Destroyer on Gojira as he sleeps, reducing him to bone. Serizawa then kills himself.

Unfortunately, Gojira would be possessed by the spirits of dead soilders from WWII who seeked vengeance against Japan for the sins of WWII. Gojira battled Mothra, Baragon, and King Ghidorah, who seeked to save Japan. Gojira killed them all.

However, the spirits of the dead monsters possessed Gojira and allowed General Tachibana to fire a submersible into Gojira's throat. When Gojira tried to use his atomic breath, he was torn to shreds.