In Egyptian mythology, the god of the afterlife and ruler of the Underworld is Osiris. Osiris is a central figure associated with resurrection, fertility, and the cycle of life and death. He is often depicted as a mummified king, symbolizing his role in the afterlife. As a god who was murdered and resurrected by his wife Isis, Osiris embodies the themes of rebirth and the eternal cycle. His reign over the Underworld reflects the ancient Egyptians' emphasis on the importance of the afterlife, including the judgment of souls and the quest for immortality through proper funerary practices.