Thanatos

Thanatos was the personification of death itself — not violent death in battle (that was the domain of the Keres), but the peaceful, inevitable end that came to every mortal. He was the son of Nyx (Night) and twin brother of Hypnos (Sleep), and the two were often depicted together.

Thanatos was imagined as a dark-winged figure who came to mortals when their time had run out. He was not malevolent but implacable — death could not be bribed, persuaded, or escaped. Only twice was he ever defeated: Heracles wrestled him to rescue Alcestis from death, and the cunning Sisyphus tricked him into chains, temporarily halting all death in the world.

When Sisyphus bound Thanatos, Ares freed him — because without death, war lost its meaning and no warriors could fall. Sisyphus was eventually punished in Tartarus for his audacity. The myth underscored the Greek understanding that death, however unwelcome, was a necessary part of the natural order.