Gyaos

Gyaos (ギャオス, Gyaosu?), is the name of several daikaiju from Daiei's Gamera film series, introduced in their 1967 production Gamera vs. Gyaos and one of Gamera's most famous opponents. It is the only Gamera foe to appear in the Showa, Heisei, and Millennium Gamera films. This makes Gyaos, arguably Gamera's arch nemesis, though Iyris and Queen Legion may also be likely candidates.

Gyaos resembles a giant cross between a pterosaur and a bat, with a flattened, arrow-shaped head, leathery wings with three claws on each, taloned feet, and a fish-like tail. It has dull blue skin in most incarnations. The Gyaos in Gamera: Guardian of the Universe had a more streamlined appearance, with larger wings and a longer neck, as well as red eyes.