Debut: Gyris and Irys
Gyaos was seen in a cutaway of all the previous Gamera villains, healing his wounds in his cave.
Gyaos appeared on Gamera's island, and briefly fought Toto before fighting gamera himself. Just when he'd gained the upper hand, the sun came up, and he fled.
Gyaos appeared in Japan from a large cavern, and feasted on blood, principally that of livestock and humans. Soon, Gamera confronted Gyaos, and after a battle, Gyaos was forced to flee, and Gamera was forced into the ocean to recover. It is soon learned that light causes Gyaos' skin to shrink, so the light of the city stadium of Nagoya kept Gyaos at bay. Gamera soon returned to finish Gyaos off and, after a battle in the air, Gyaos cut off his own foot to escape from the sun. The protagonists developed a plan to place artificial blood on a rooftop in Nagoya. The plan was to keep Gyaos drinking the blood for so long that the sun would come up and kill him. But Gyaos proved more cunning than originally thought and used a strange fog attack to protect himself from the sun. The next plan was to lure Gamera to Gyaos' lair in the forest by setting the forest alight. Gyaos used his fog attack to put out the flames, but Gamera arrived and eventually defeated Gyaos by throwing the beast into a volcano. Gyaos, unbeknownst to Gamera, hung onto the side of the volcano and escaped after Gamera left, retreating into his cave to heal his wounds.
Gyaos resembles a giant pterosaur or bat-like creature, with a flattened, arrow shaped head, leathery wings with three claws on each, taloned feet and a long-ish flat tail. Gyaos' neck can move up and down, but cannot move side to side much due to having a special fork-shaped throat that allows him to fire his sonic screech. He can, however, tilt his head side to side. His skin appears to be a dark lavender with red highlights, but in the dark, it appears to be almost entirely black.
Gyaos is a kaiju that relies entirely on bestial urges and instinct, but can quickly become cunning should the situation get too out of his favor. He feeds upon weaker species and attacks without remorse.
- Flight: Gyaos is capable of flight at Mach 4.
- Sonic Cutter Beam: Gyaos can fire an amazingly precise beam from his mouth through the use of a special fork-shaped throat. It can slice objects into halves.
- Fog: Gyaos can emit fog from his body to obscure the sun, douse flames, and disrupt technology.
- Regeneration: Gyaos can regenerate at a slow-to moderate pace. Drinking blood speeds up this process greatly.
- Sharp Teeth and Talons: Gyaos' teeth and claws are absurdly sharp, able to slice even through tough hides.
- Triangular head allows for powerful ramming attacks.
- Fighting style is very savage.
- He originally belonged to Goldn, who gave him to Krazar, who gave him to IFIE.