The Egyptian god of the underworld, as referenced in the New York Times Crossword on September 29, 2025, is Osiris. He is known as the ruler and judge of the dead, overseeing the realm of the dead and afterlife, and is often depicted holding a shepherd's crook and flail. Osiris symbolizes death, resurrection, and the cycle of life, particularly the flooding of the Nile River that brought fertility to the land.