Utnapishtim is the flood survivor who boards an ark in the Epic of Gilgamesh.
In the Babylonian flood story embedded in the Epic of Gilgamesh, the god Ea warns Utnapishtim to build a large boat and preserve life from a coming flood. Utnapishtim follows the instructions, brings aboard family members, craftsmen, and animals, and survives when the waters cover the land.
The account is often compared with the story of Noah because both feature a divinely warned survivor, a large vessel, animals, a devastating flood, and birds sent out after the waters subside. They are not the same narrative, however. Utnapishtim is a character in Mesopotamian literature, while Noah belongs to the Hebrew Bible and later Jewish, Christian, and Islamic traditions.
A common mistake is to answer Gilgamesh, the epic’s hero. Gilgamesh meets Utnapishtim and hears his story, but Gilgamesh does not build or board the flood vessel in that episode. Enkidu is Gilgamesh’s companion, not the flood survivor.