The Flood-Hero Granted Eternal Life
One man outlived the Flood and was made deathless — the single exception the next hero crosses the world to find.
Also: Ziusudra · Utnapishtim · Uta-napishti · flood hero immortality · eternal life granted · the distant one
Having survived the Flood, the hero is rewarded as no other mortal: the gods grant him eternal life and settle him in a remote place beyond ordinary reach. In Sumerian he is Ziusudra ('life of long days'), placed in Dilmun; in the Gilgamesh epic he is Utnapishtim, whom Gilgamesh seeks out precisely because he alone among humans has escaped death. From him Gilgamesh learns the hard truth that this gift will not be repeated — immortality was a one-time divine exception, not a path open to others. The motif ties the Flood tradition directly to Mesopotamia's deepest meditation on death.
In short
The motif of the Flood-survivor (Ziusudra / Utnapishtim) being uniquely granted immortality and removed to a far place — the one human exception to mortality, whom Gilgameš seeks.
Where it’s found
'The Flood story' (Ziusudra; ETCSL 1.7.4, in corpus); Gilgameš XI (Utnapishtim; akkadian-pending; George)
How the idea developed across Sumer, Babylon & Assyria
The granting of immortality to the Flood-hero is explicit in both the Sumerian Flood story (Ziusudra in Dilmun) and Gilgameš XI (Utnapishtim 'made like the gods'); it is the narrative hinge linking the Flood to the immortality-quest. Distinct from any biblical figure — Genesis does not make Noah immortal.
Ziusudra/Utnapishtim is a LEGENDARY figure of myth, not a historical person.