Gilgamesh and Enkidu.
Gilgamesh was the king in/of Uruk of southern Babylonia and known as an autocratic, tyrant and abuser of his powers as king. While not a very nice way to start the story with a hero but as Andrew George notes; the poet who composed the piece tried to make Gilgamesh human, with all the follies that go with ultimate power and authority.
The gods of Sumer heard the pleas and lamentations of Gilgamesh' people and decided to do something about it. They send in a "wildman"1 called Enkidu, as powerful as Gilgamesh but without the flaws Gilgamesh exhibited while "drunk on power".
Gilgamesh is a man of the city while Enkidu is a man of the wild. Enkidu goes to the city of Uruk to meet Gilgamesh with his own equal power, and stop Gilgamesh from abusing his people. After learning how to basically, be human (transitioning from a "wildman"), Enkidu meets Gilgamesh to teach him a lesson in humility and fairness.
Gilgamesh and Enkidu get into a big fight and struggle for some time until finally coming to a complete standstill since they where equally matched in power. After coming to a standstill they recognize in each other a best friend, something they became and remained until Enkidu's death after many adventures.
Together they slayed the monster Humbaba and the Bull of Heaven, and for this Enkidu is punished by the gods and dies. The deep and tragic loss of Enkidu prompted Gilgamesh to undertake a quest to escape death by obtaining immortality.
1: Noted by Wikipedia
The apparition of Enkidu as a primitive man seems to be an innovation
of the Old Babylonian version (1300 - 1000 BC), as he was originally a
servant-warrior in the Sumerian poems.
The Babylonian Gilgamesh epic : introduction, critical edition and cuneiform texts by A.R George
The epic of Gilgamesh: the Babylonian epic poem and other texts in Akkadian and Sumerian A.R George
The Epic of Gilgamesh, Lecture by Andrew George