The Nahuatl name Itztlacoliuhqui is usually translated into English as "Curved Obsidian Blade". J. Richard Andrews contends that this is a mistranslation, and that the correct interpretation is "Everything Has Become Bent by Means of Coldness", or "Plant-Killer-Frost".
The creation of this god appeared in the Aztec myth of creation. Tonatiuh, the Sun god, demanded obedience and sacrifice from the other gods before he will move. Enraged at his arrogance, the god of dawn and the planet Venus, Tlahuizcalpantecuhtli, shoots an arrow at the Sun. However, the dart misses its mark, and the Sun throws his own back at the morning star, piercing the Lord of Dawn through the head. At this moment, Tlahuizcalpantecuhtli is transformed into the god of obsidian stone and coldness, Itztlacoliuhqui.
Itztlacoliuhqui is a part of a holy trinity of birth, life, and death. He takes the place of death in this particular trinity. Birth is taken by Tezcatlipoca and life by Itzpapalotl, Itztlacoliuhqui's female counterpart.