Godzilla

Godzilla (ゴジラ Gojira) is a kaiju that appeared in 1954. He is the undisputed king of the monsters and is considered to be among one of the most powerful kaiju on earth.

Origin
Godzilla is a Godzillasaurus, type of theropod dinosaur from the late Cretaceous period. He lived on Odo island with other members of his kind before being disturbed and enhanced by an American hydrogen bomb test. Dr. Kyohei Yamane proposes that Godzilla might have been living among others of his kind prior to the detonation, but the H-bomb completely destroyed his habitat, as well as killing his companions and burning and enraging Godzilla, which drew him out. This idea is supported by large oceanic caves deep beneath oceans worldwide, indicating Godzilla was possibly living with other Godzillas underwater before a huge explosion destroys his habitat, and drawing him to the surface. After the original Godzilla was though to be killed, Yamane proposes that other Godzillas may have survived to the present day and could be awakened by future nuclear tests.

History
Godzilla is a Godzillasaurus who became irradiated when an American hydrogen bomb test conducted in the Pacific Ocean in 1954, which destroyed his habitat (and his companions) and drew him to the surface. Godzilla took his rage upon humanity, destroying ships within his vicinity and eventually ravaged Odo Island as well as Tokyo. Dr. Daisuke Serizawa, a Japanese scientist, took it upon himself to end Godzilla using his invention, the Oxygen Destroyer, while taking his own life in the process in order to ensure that the weapon could never be used again. Unfortunately, Godzilla survived, though he did not appear, as he swam away into the depths of the seas. Godzilla later reappeared in 1955 to battle another kaiju, named Anguirus.