Also known as the Death Bat and Sudden Bloodletter, Camazotz was the bat god of the ancient Mayan people. This vampiric winged demon was the god of darkness, violence, and sacrifice (especially blood sacrifice). The name Camazotz itself is derived from two words in the K'iche' language: kame, which means "death," and sotz', meaning "bat." Camazotz was said to inhabit Xibalba, the Mayan version of Hell. This nightmarish creature reveled in the slaughter of innocent people, and was said to be especially fond of drinking human blood. Those who devoted themselves to this deity would open a vein, fill a wooden or ceramic bowl with their blood, and would offer it up to the Death Bat. He is depicted as being a sacred vampire.
Originally, Camazotz was an anthropomorphic bat-monster worshipped by the Zapotec Indians of Oaxaca, and was later adopted by the Mayans as a vampire god that demanded offerings of blood from it's followers in exchange for the deity's favors or aid. The cult of Camazotz itself began sometime around 100 B.C. Camazotz is featured prominently in the Popul Vuh, a compendium of Mayan mythology and beliefs. In Xibalba, the demon presides over a house of gigantic bat-creatures like himself in Zotzilaha (in what is now Guatemala), the only difference being that they acknowledge the Death Bat as their lord and master.
One legend tells of the Mayan Hero Twins Hunahpu and Xbalanque encountering Camazotz and his kin during their trials in the underworld. The twins had to squeeze themselves into their own blowguns to protect themselves from the circling bats. Hunahpu made the mistake of sticking his head out to see if the sun had risen. Camazotz himself immediately snatched his head off and flew up to the ballcourt, where the head would be used as the ball by the gods in their next ballgame. Xbalanque then calls upon every animal in the forest to bring him their favorite foods. One of these animals brings him a squash, from which Xbalanque carves his brother a new head. The brothers continue on through Xibalba, finally finding and defeating Camazotz (as well as other lords of the underworld), banishing him from creation.
It is thought by some that the legend of Camazotz may in fact be derived from the prehistoric vampire bat, Desmodus Draculae, or the Giant Vampire Bat. This bat is twenty-five percent larger than the common vampire bat (Desmodus Rotundus), and fossilized remains have been found that date back as recently as ten thousand years ago. Some think that D. Draculae may still be around today, and was apparently still common around the time of the Mayans. But is there something else to the legend, perhaps something supernatural? Possibly. They may never know for sure.
Sources
http://en.m.wikipedia.org/wiki/Camazotz#section_1
http://www.blueroadrunner.com/camazotz.htm
http://ferrebeekeeper.wordpress.com/2011/04/06/camazotz-the-death-bat/
Camazotz, Mayan God of Bats