Aztec mythology is the body or collection of myths of the Aztec civilization of Central Mexico. The Aztecs were Nahuatl-speaking groups living in central Mexico and much of their mythology is similar to that of other Mesoamerican cultures. According to legend, the various groups who were to become the Aztecs arrived from the north into the Anahuac valley around Lake Texcoco. The location of this valley and lake of destination is clear – it is the heart of modern Mexico City – but little can be known with certainty about the origin of the Aztec. There are different accounts of their origin. In the myth the ancestors of the Mexica/Aztec came from a place in the north called Aztlan, the last of seven nahuatlacas to make the journey southward, hence their name "Azteca." Other accounts cite their origin in Chicomoztoc, "the place of the seven caves", or at Tamoanchan.

The Aztecs were a Mesoamerican culture that flourished in central Mexico in the post-classic period from 1300 to 1521. The Aztec people included different ethnic groups of central Mexico, particularly those groups who spoke the Nahuatl language and who dominated large parts of Mesoamerica from the 14th to the 16th centuries. Aztec culture was organized into city-states (altepetl), some of which joined to form alliances, political confederations, or empires. The Aztec Empire was a confederation of three city-states established in 1427: Tenochtitlan, city-state of the Mexica or Tenochca, Texcoco, and Tlacopan, previously part of the Tepanec empire, whose dominant power was Azcapotzalco. Although the term Aztecs is often narrowly restricted to the Mexica of Tenochtitlan, it is also broadly used to refer to Nahua polities or peoples of central Mexico in the prehispanic era, as well as the Spanish colonial era (1521–1821). The definitions of Aztec and Aztecs have long been the topic of scholarly discussion ever since German scientist Alexander von Humboldt established its common usage in the early 19th century.