Huehueteotl (from huēhueh "old" and teōtl "god" in Nahuatl) is a Mesoamerican deity figuring in the pantheons of pre-Columbian cultures, particularly in Aztec mythology and others of the Central Mexico region. He is also sometimes called Ueueteotl. Although known mostly in the cultures of that region, images and iconography depicting Huehueteotl have been found at other archaeological sites across Mesoamerica, such as in the Gulf region, western Mexico, Protoclassic-era sites in the Guatemalan highlands such as Kaminaljuyú and Late-Postclassic sites on the northern Yucatán Peninsula (Miller and Taube, 1993:189).
Huehueteotl is frequently considered to overlap with, or be another aspect of, a central Mexican/Aztec deity associated with fire, Xiuhtecuhtli. In particular, the Florentine Codex identifies Huehueteotl as an alternative epithet for Xiutecuhtli, and consequently that deity is sometimes referred to as Xiutecuhtli-Huehueteotl.
However, Huehueteotl is characteristically depicted as an aged or even decrepit being, whereas Xiutecuhtli's appearance is much more youthful and vigorous, and he has a marked association with rulership and (youthful) warriors.
Read more about Huehueteotl: Worship