In 2004 film Godzilla Final Wars, Gigan was a cyborg kaiju created by a mysterious alien race known as the Xiliens. It is not known where he first came from, or what he originally looked like, but we know that Gigan served the people of Planet X for an extremely long time prior to their first invasion of Earth. It's likely that, by the time of the film, he had been rebuilt and upgraded so many times that his original form would be unrecognizable.
Humanity was created by the Xiliens as a food source, which they would return to every few thousand years. However, by the time of 10,000 BCE, humanity had advanced much further than their unseen lords had wished. To make sure their cattle would stay as just that, the X aliens launched a full scale attack on the civilizations of ancient Earth. Gigan was the trumph card of this first invasion, and made short work of everything that stood in his masters' way. The cyberpunk space monster not only annihalated entire nationstates, but sunk multiple of the planet's continents and slaughtered the guardian monster, Mothra, before he was finally called off. However, the Xiliens still weren't satisfied. Knowing that humanity could one day rise again, the invaders left their weapon behind in stasis, waiting for the day he would be called upon to cull the herd once more...
12,000 years of slumber passed until the modern day Earth Defense Force discovered Gigan's mummified body off the coast of Hokkaido. Gigan was brought to a research facility near the EDF's headquarters to be studied, unknowingly alerting the Xiliens. The initial Xilien leader tried subterfuge, but once the aliens were found out and a resulting coup led to his death, the new Controller of Planet X awakened Gigan to rampage across Japan.
Breaking out of his mummified shell, the cyborg wasted no time wiping out everything in sight, obliterating the EDF's HQ in a single laser blast. With the help of countless mind controlled Earth monsters, it took little more than a day for Gigan and his Xilien masters to utterly crush the cattle. The final hurdle came in the form of the only surviving EDF warship, Gotengo, revealing itself to have survived and making its way toward an Antarctic outpost.
By the personal request of Planet X's leader, Gigan took off after the Gotengo, intercepting it around a kilometer off of "Area G". The Gotengo tried to fight back, but all of its efforts were proven useless as Gigan easily dodged their missiles and knocked them out of the sky within seconds. However, as the cyberclaw terror circled in for the kill, the Gotengo's missiles looped around and blew Area G apart.
Gigan was totally blindsided by a thermonuclear ray crashing into his chest from the wreckage. Godzilla, who had been locked under the ice for decades, had finally woken up, and began venting his fury on everything in sight. Falling back, Gigan took to the skies and blasted Godzilla from above, before dropping back down and attacking Godzilla with grappling cables. The King of the Monsters was ensnared by the wires, rendered helpless as Gigan slowly pulled him towards the spinning buzzsaw which sprawled across his torso.
Just as it looked like all was lost, and the nuclear monster was to be sawed in two, Gigan was taught a harsh lesson in underestimating Earth's ultimate weapon. Godzilla fired an Atomic Ray directly into Gigan's face at point blank range, blowing the cybernetic kaiju's head clean off his neck. As the extraterrestrial's body slumped over and crashed to the icy ground, Godzilla ripped the cables from his neck and roared in triumph.
Though he had been defeated, the sadistic space monster's story was not yet done. As Godzilla left the frozen continent, the Xiliens recovered Gigan's lifeless body, reconstructing his destroyed head and equipping him with additional armor and even deadlier weapons. The next night, when Godzilla had made his way into the heart of Tokyo for one final battle, Gigan was fully revived and ready for battle once more.
When a descendant of Mothra, likely the offspring of the one Gigan had killed so long ago, attempted to intervene on Godzilla's behalf, the Modified Gigan was deployed to intercept. The two came to blows over Tokyo Tower, repeatedly striking one another head on before coming to an effortless landing. Mothra's hurricane winds proved ineffective against Gigan when he slammed his dual chainsaw blades into the pavement, using the powerful tools as equally powerful tank treads.
Mothra found herself unable to react in time to stop Gigan's bladed tail from puncturing her abdomen, grabbing hold and flinging her across the cityscape. Before she could fully recover, the divine moth found herself on the retreat as her opponent shot after her. Mothra attempted to fly away, but Gigan was faster, and managed to clip her wing with one of his gargantuan saws. Losing control, the mammoth moth fell from the sky, slamming face first into the ground below. With one foe down, Gigan turned his back to his defeated enemy and made his way toward Godzilla.
As Godzilla engaged Monster X, a mysterious beast from Planet X, Gigan blasted Godzilla in the back, dropping down for round 2. Almost instantly, Godzilla found himself outmatched, being held down by Monster X as his artificial ally methodically tore Godzilla's chest open. Quick thinking by the King of the Monsters allowed him to get out of the duo's hold by tricking the space monsters into striking one another, but Godzilla still found himself facing an uphill battle. Luckily, before the Xilien kaiju could attack him once more, a recovered Mothra swooped down from the cloudy skies and slammed both aliens into the dirt with her mighty wings. Getting back to their feet, Gigan and Monster X split up to take on their shared enemies. While the skeletal beast re-engaged Godzilla, Gigan chased after Mothra, intent to settle the score once and for all.
When the two began to clash once more, Mothra defensively deployed poison powder from her wings. Gigan fired off a pair of tracking discs, both of which were easily evaded by the deity, but they had never been intended to strike her in the first place. Distracted by dodging one attack, Mothra was left completely open when Gigan blasted her scale cloud with his energy laser. The scales instantly ignited, and Mothra was helpless as her entire world turned to flame. As the fire rose hundreds of meters into the sky, Gigan turned his back to the conflagration, striking a pose in victory.
Unfortunately, what Gigan didn't know was that his foe's scales were no only poisonous, but also held the ability to disrupt electrical signals. The computer systems of his blades were fried, and unable to detect anything in the sea of fire which consumed Mothra, they automatically chose Gigan as their target. The cyborg's neck was slashed open on both sides by the homing discs, and while they seemed inneffective at first, the truth became painfully apparent when he turned back toward the wall of fire and activated his chainsaws.
At the points of impact, explosions of sparks heralded disaster. Gigan's head fell from his neck once again, plummeting down to his feet. Even still, the cyberpunk space monster tried to persist. He only took a single step toward Mothra's apparent grave when she launched herself, completely engulfed in fire, straight at Gigan's chest. Fueled by her sheer speed and heat, she burned through his internal machinery, sparking an explosion even larger than the one which had nearly taken her life. Fire ripped through Gigan's body, his armor blew away in blackened chunks. In one final blast, the cyborg was defeated. A single bloody chainsaw impaled the ground behind his severed head, marking Gigan's final resting spot. Moments later, the Xilien Mothership, along with everything inside it, were blown to pieces by the Gotengo. At long last, the threat of Gigan and his masters was no more.
