In Aztec mythology, (and among the Toltecs), Xolotl was the god of lightning and the one who aided the dead on their journey to Mictlan. He was the twin of Quetzalcoatl (both sons of the virgin Coatlicue) and the personification of Venus, the evening star. He guarded the sun when it went through the underworld at night. In art, Xolotl was depicted as a skeleton or a dog-headed man. He was also the patron of the Ulama game.
In Aztec and Toltec mythology, Xolotl ("The Animal", Lord of the Evening Star, Lord of the Underworld) was the god of lightning and a psychopomp, which is to say that he was the one who aided the dead on their journey to Mictlan, the afterlife.
As lord of the evening star and personification of Venus, he pushes the sun at sunset towards the ocean and guards her during the night on her dangerous journey through the underworld.
Xolotl is represented as a skeleton, or as a man with the head of a dog.