Ah Puch is one of several names, drawn from colonial-period Yucatec sources, for the Maya god of death, the deity whom modern scholars, working from the surviving Maya books, label God A in the codices, and who is also known by the name Yum Cimil, Lord of Death. It is worth being precise about how he is known: much of our knowledge of the Maya gods comes from the handful of screenfold bark-paper books that survived the burning of the Maya libraries after the Spanish conquest, together with sculpture and painted pottery, and scholars have assigned letters to the recurring deities before their ancient names could always be securely read.
In the codices the death god appears as a skeleton or as a bloated, decaying corpse marked with the black spots of putrefaction and hung with bells, sometimes with an owl, a bird of ill omen and death across Mesoamerica, as his companion. He belongs to Xibalba (Metnal in Yucatec), the Maya underworld, a place of fear and disease imagined in some detail in Maya thought. As the personification of death, decay and the diseases that bring it, he stands opposed to the gods of life and maize, and Maya art sometimes pairs the two, life and death, the maize god and the death god, as the poles of existence. The Maya are a living people, and death and the ancestors remain meaningful in contemporary Maya communities; the skeletal god of the ancient codices, however, is known to us chiefly through those old books and the scholarly reconstruction of the religion they record, and honesty requires acknowledging that his ancient name and full character are only partly recovered.