Godzilla (Gojira in Japan) is a mutant dinosaur and the King of the Monsters. Originally a lost dinosaur, a Godzillasaurus, he was revived and heavily mutated by nuclear weapons tests. Capable of breathing atomic fire and unable to be killed by conventional weapons, throughout all his incarnations Godzilla has gone from being a full-scale threat to humanity, to Earth's mightiest champion and back to being a threat again, yet his power and destructive capabilities, the monster being a symbol of atomic weaponry, cannot be disputed.
Godzilla made his grand debut in 1954. He was a mere urban legend upon a small island until he emerged and began wreaking havoc. His trail of destruction led to Tokyo where he went on a massive rampage and turn the city into a sea of fire overnight. The only hope of getting rid of the monster was to use Dr. Serizawa's Oxygen Destroyer, which had the capability to kill every living thing in water. The machine was deployed successfully, and Godzilla, bones and all, was wiped off the face of the Earth along with Serizawa, who martyred himself to prevent knowledge of the Oxygen Destroyer coming into the wrong hands. Japan was saved, but the monster's rampage was another wake-up call about the dangers of nuclear weaponry. Another Godzilla could appear one day. And indeed, one did....
In 1985, following a reboot of the films' continuity, a second Godzilla emerged in the footsteps of the original. This Godzilla would only go from strength to strength, becoming stronger with each confrontation, even moreso when he was believed to have been wiped from history, and was accidentally given a power and size boost. Following the death of Rodan, his atomic breath became stronger too. But a short time later, an even bigger threat to Japan emerged. Birth Island, where Godzilla and his young son were living, was completely destroyed by Godzilla. The monster had begun to give off enormous amounts of radioactivity. His heart, which in itself was like a nuclear reactor, was showing signs of an imminent meltdown. When this happened, Godzilla would die, sink into the depths of the Earth with the sheer heat, and destroy all. The situation was exacerbated by the arrival of Destoroyah, an army of creatures spawned from Serizawa's Oxygen Destroyer. Godzilla battled against them as they mutated into one larger monster, his power increased by his meltdown. It was a long and gruelling battle, with Godzilla in agony and later consumed with grief and rage at the loss of his son who was dropped from a great height by Destoroyah. Eventually, when the King of the Monsters' meltdown began, the Japan Self-Defence Forces were able to use ice weapons to counter the heat and prevent Godzilla's death from destroying the Earth. In his final moments, Godzilla gave out one last weak roar before collapsing into a pile of molten flesh and bone. It was a pyrrhic victory: the Earth had lost its greatest champion, and Tokyo was a radioactive ghost town, until the radiation levels began dropping. Godzilla lived on in death. His son's body had absorbed the excess radiation and grown to full size: Junior was ready to take his place as the new King of the Monsters.
Since much of the Millennium films are self-contained sequels to the 1954 original, Godzilla has only been actually seen to die in this era once. The first instance was in Godzilla, Mothra and King Ghidorah: Giant Monsters All-Out Attack. In this film, Godzilla was a physical embodiment of the souls of Japanese soldiers, enraged that their sacrifices have been forgotten. After defeating King Ghidorah, the last Guardian Monster, Godzilla was dragged to the bottom of the sea by the Guardians' spirits. A missile was planted in a wound Godzilla sustained in his battle with Ghidorah, and he was brought down by the missile's explosion, later disintegrating. Yet, his heart remained at the bottom of the sea, still beating.