Gilgamesh is a great sumerian god (demigod according some versions), he is inspired on a real king, is the protagonist of the first story ever wrote, an epic poem, where is told how he tries to become inmortal and his motives to do it around all his life.
His poem has the first version of the legend of the flood, sumerian version of the tale of the ark of Noah.
The oldest version of the poem was wrote in Uruk (now Iraq) around the time and the same region of the priestess-queen Hedu Anna (either called Enheduanna), the first person to sign a document.