Q (1982)
This is the only movie I'm aware of that's about the Aztec feathered serpent god Quetzalcoatl. In its 1982 incarnation, it's a schlocky monster movie set, inexplicably, in New York City. However, change the setting to southern Mexico and make Quetzalcoatl more of a terrifying, incomprehensible force of nature and I think you have the beginnings of good horror movie or even, if handled correctly, some kind of psychological terror. I think Guillermo del Toro could make something great out of this.