MUTO
Region of origin: The Philippines
Taking its name from the acronym given to the broader classification it belongs to (Massive Unidentified Terretrial Organism), the MUTO were ancient proto-insectoid creatures that parasitized the other giant creatures that occupied the primordial earth, the young MUTO spending the early stages of their life in the bodies of their hosts, feeding off the residual radiation these other creatures consumed. Having consumed enough energy, the MUTO would eventually enter a chrysalis stage, from which they would emerge and carve their way out of the host body. Two of these chrysalises would survive undisturbed for millions of years in a cavern deep beneath the Philippines before human excavations disturbed them, leading to the creatures waking up and seeking out new sources of energy to consume and a location to reproduce, their instincts driving them on a path of destruction through the modern world before a similarly awakened giant creature was able to stop them. You know the one. The MUTO are sexually dimorphic, with the males being much smaller than the female and possessing midlegs that have developed into flat, glider-like structures that can function as wings.
The Compendium of Arcane Beasts and Critters 