Quetzalcoatl ("feathered snake") is the Aztec name for the Feathered-Serpent deity of ancient Mesoamerica, one of the main gods of many Mexican and northern Central American civilizations.
Classic Maya depiction from Yaxchilan
The Feathered Serpent deity was important in art and religion in most of Mesoamerica for close to 2,000 years, from the Pre-Classic era until the Spanish Conquest. Civilizations worshiping the Feathered Serpent included the Olmec, the Mixtec, the Toltec, the Aztec, and the Maya.
The worship of Quetzalcoatl sometimes included human sacrifices, although in other traditions Quetzalcoatl was said to oppose human sacrifice.
Mesoamerican priests and kings would sometimes take the name of a deity they were associated with, so Quetzalcoatl and Kukulcan are also the names of historical persons.
One noted Post-Classic Toltec ruler was named Quetzalcoatl; he may be the same individual as the Kukulcan who invaded Yucatan at about the same time. The Mixtec also recorded a ruler named for the Feathered Serpent. In the 10th century a ruler closely associated with Quetzalcoatl ruled the Toltecs; his name was Topiltzin Ce Acatl Quetzalcoatl. This ruler was said to be the son of either the great Chichimeca warror, Mixcoatl and the Colhuacano woman Chimalman, or of their descendant.
The Toltecs had a dualistic belief system. Quetzalcoatl's opposite was Tezcatlipoca, who supposedly sent Quetzalcoatl into exile. Alternatively, he left willingly on a raft of snakes, promising to return.
The exact significance and attributes of Quetzalcoatl varied somewhat between civilizations and through history. Quetzalcoatl was often considered the god of the morning star and his twin brother, Xolotl was the evening star (Venus). As the morning star he was known under the title Tlahuizcalpantecuhtli, which means literaly "the lord of the star of the dawn". He was known as the inventor of books and the calendar, the giver of maize corn to mankind, and sometime as a symbol of death and resurrection. Quetzalcoatl was also the patron of the priests and the title of the Aztec high priest.
Most Mesoamerican beliefs included cycles of worlds. Usually, our current time was considered the fifth world, the previous four having been destroyed by flood, fire and the like. Quetzalcoatl allegedly went to Mictlan, the underworld, and created fifth world-mankind from the bones of the previous races (with the help of Cihuacoatl), using his own blood to imbue the bones with new life.