Who was Gilgamesh's arch enemy?

Answer 1

Gilgamesh doesn't really have an arch enemy. He encounters, or more accurately, makes various enemies throughout the epic but there is no single "arch" enemy that opposes him at every turn. These incidental enemies include Enkidu, Humbaba, Ishtar, the Bull of Heaven, and the mysterious stone crew of the ferryman. Note that it is usually Gilgamesh himself who creates these enmities by his actions. In fact, the best candidate for the position of arch enemy is Gilgamesh himself!

The fight with Enkidu only happens because Gilgamesh oppresses his own citizens. Gilgamesh kills Humbaba to obtain personal glory but the end result is the ignominious death of his best friend. Ishtar sends the Bull of Heaven because Gilgamesh insults her and the slaughter of the "stone ones" is an unnecessary and misguided act of violence. He even considers attaching Utnapishtim at one stage. The fight with Enkidu aside, all of these violent episodes ultimately work against Gilgmaesh's best interests. Setting out to achieve fame and immortality, he achieves neither in the way he had anticipated. The wisdom he eventually acquires at the very end of the epic seems to include the insight that it is better to nurture life than to destroy it. Perhaps this is why the list of his achievements in the introduction to chapter one lacks any reference to the slaying of monsters.

Answer 2

Enkidu was Gilgamesh's companion from the epic of Gilgamesh

Answer 3

Gilgamesh's arch-enemy was the wild man Enkidu, whom he eventually befriended. Together, they faced Humbaba, the guardian of the Cedar Forest, as one of their primary adversaries.