Gigan Rex (ガイガンレクス is an alien Gaigan Rekusu)kaiju who appears in Takuya Uenishi's 2022 Godzilla short film Godzilla vs. Gigan Rex. After an attack on Earth by a group of Gigan Miles that was repulsed by Godzilla, the powerful Gigan Rex appeared with an army of the cyborgs to challenge the King of the Monsters once more.
Gigan's Japanese name, Gaigan, was derived from a nickname for actor Yujiro Ishihara, "Nice Guy" (ナイスガイ, combined with the word for goose, gan naisu gai) (雁). Both were influences on Gigan's design in his visor and body shape, respectively. The name may have also been chosen as a contraction of "geiger counter," spelled in Japanese as ガイガーカウンター (gaigā kauntā). The Rex in Gigan Rex's name is the Latin word for "king." It is transliterated into Japanese as Rekusu (レクス), which differs from the spelling rekkusu (レックス) used in the Japanese name of Tyrannosaurus rex by one sokuon.
Gigan Rex appears largely similar to the Gigan Miles, but with a differing chest pattern, coloration, and appendages. His skin is a metallic red instead of blue-green, dark grey skin-like material is present across his chest in place of Gigan's golden scales, and his visor is magenta rather than red. Gigan Rex lacks the buzzsaw typical of Gigan designs, instead sporting an eyelid-like structure on his sternum which can open to reveal a dark object akin to the Miles' forehead apertures. Instead of hooks, the monster's arms are tipped with sword-like blades which and are able to extend out into whips which are lined with segments of the blades. Gigan Rex possesses a long tail which terminates in a forked blade.
After besting a group of Gigan Miles, Godzilla drew the attention of an even stronger foe: Gigan Rex. Touching down behind Godzilla, Gigan Rex extended his forearm blades into whips and struck Godzilla twice before flooring him with a blast from his chest laser. Gigan Rex evaded Godzilla's atomic breath and attempted to swipe him with his whips, cutting two buildings clean in half in the process. Godzilla caught the whips in his hands, however, and pulled Gigan Rex toward him. Godzilla knocked Gigan Rex away with his tail and began blasting him with a continuous stream of atomic breath, but the cyborg blocked it with his claws long enough for more Miles to arrive. As the Miles dive-bombed Godzilla with their buzzsaws, Gigan Rex joined in with blasts from his chest laser. Four of the Miles attempted to surround Godzilla, slicing him with their buzzsaws from every direction, but were annihilated by an atomic pulse. Godzilla began to glow white and shot down one of the Miles with an even stronger atomic breath, causing the surrounding area to erupt violently into flames. Hovering above Godzilla, Gigan Rex harvested the remaining Miles' energy cores telepathically and attached them to his blade whips, empowering his chest laser. Godzilla and Gigan Rex locked beams, and though Rex initially appeared to be overpowering the King of the Monsters, Godzilla managed to push the point of collision into Rex, killing the creature in an explosion.
Godzilla vs. Megalon (2023)
In an underground cavern beneath a Japanese military facility, Gigan Rex's maimed corpse laid attached to many wires siphoning bright red energy and transferring it to a space in the wall shrouded in shadow as a Seatopian woman held up a spiked, engraved stone. Seeking revenge on humanity, she declared a sacrifice of the "beast of Sorabito" to awaken the monster Megalon. Gigan Rex flashed red and the wires attached to it surged with energy, which flowed into and illuminated a large object resembling the stone she held.
Gigan Rex's primary melee weapons are the Rex Blades (レクスブレード he sports on his forearms. These blades can be extended into saw-toothed whips, which were powerful enough to slice through buildings. Rekusu Burēdo)
Whilst in solid blade form, the Rex Blades are capable of blocking Godzilla's atomic breath for an extended period of time with no sign of damage.
Gigan Rex can open the crevice on his chest to reveal a beam-firing aperture. Its initial laser, which was yellow in coloration, managed to knock Godzilla off of his feet.
After Rex absorbed the energy of the Gigan Miles' cores, the beam became thicker and red. Though this powered-up beam never collided with Godzilla, it initially overpowered the monster's white-hot atomic breath in a Beam-Fight.
Gigan Rex possesses a forked spike at the tip of his tail. Though he never used it as a weapon, he managed to stab it through a building in an attempt to stabilize himself.
Gigan Rex appears to communicate with the Gigan Miles telepathically. The gem on his forehead glows and flashes purple while doing so. Rex was also able to telekinetically extract the Miles' cores.
Like the Gigan Miles, Gigan Rex is capable of flight through levitation; he could both propel himself and hover in midair. When he first appeared on screen, he flew to the ground so quickly that he could only be perceived as a blur. He is also capable of leaping high into the air.
Unlike his subordinates, Gigan Rex is able to withstand both Godzilla's physical attacks and his atomic breath. He was unharmed from colliding with the ground after flying so quickly that he could not be clearly perceived.
- Main article: Gigan Rex/Gallery.
Gigan Rex utilizes pitched-down Gigan roars.
This is a list of references for Gigan Rex. These citations are used to identify the reliable sources on which this article is based. These references appear inside articles in the form of superscript numbers, which look like this: 
- Ozawa, Ryoko; Tomoi, Taketo; Nakamura, Satoshi, eds. (4 September 2016). All Toho Monsters Pictorial Book (4th ed.). Yosensha. ISBN 978-4-8003-0362-2.