The Epic of Gilgamesh
Gilgamesh: He is the king of Uruk, part god. The death of his best friend Enkidu causes him to fear death very deeply, and he goes on a quest to find immortality. He has to brave several tests of courage, and has to withstand the lack of support by the gods. He eventually finds it, but loses it. So, he goes back with empty hands, but he has learned the inevitability of death and learns to accept it.
Enkidu: Gilgamesh's best friend, created by the gods out of clay. He came to defeat Gilgamesh at wrestling, but they ended up becoming very good friends. Together, they braved many dangers. He becomes ill and dies, sending Gilgamesh on his quest for immortality due to his fear of death.
Utnapishtim: The survivor of a flood sent by the gods to destroy all humans. For his reward, he and his wife were given eternal life. He was actually given a heads-up by the god Ea, who told his house to become a boat so that some people might live.