In Sumerian mythology, the ruler of the underworld is Enlil, who oversees the realm of the dead and governs the fates of souls. Known as a powerful god associated with wind, air, and storms, Enlil also embodies the dual nature of creation and destruction. His rule indicates a belief in the cycles of life and death, reflecting the Sumerians’ understanding of mortality and the afterlife as interwoven with the living world's dynamics.