The song Headstrong by Trapt displays Gilgamesh's strength he has inside, that he wants to seen as a God even though he is only 2/3rds of it. He is physically fit and is a wise man, nothing can seem to stop him. Just like in this song, he can take on anyone because he is mentally strong as well as physically. Gilgamesh can fight anyone because he is part God, resulting in him being able to beat any apponent.
The song What Hurts The Most by Rascal Flatts is perfect for when Gilgamesh's best friend Enkidu dies of an illness. Gilgamesh was heart broken and upset when it happened. Just like this song, he has to carry on with his life and move on with things, no matter how much it hurt to lose a best friend. After all, it was his fault that Enkidu died, the gods inflicted the illness onto him because it was punishment for killing the bull together.
The song Invincible by Two Steps From Hell is a great song for the battle scene between Enkidu, Gilgamesh and Humbaba. Humbaba is the demon bull sent down to punish Gilgamesh for all the things he has done. They wrestle with Humbaba and eventually end up killing him. This song is instrumental and the instruments being used are loud and clashing just like the fight is.
The song Over My Head by The Fray fits Gilgamesh's failures at becoming immortal. When he has to stay awake for a week and fails, or when he loses the plant that restores youth. It just proves that he could never be immortal, that he is still a man. No matter how hard he tries, it's obvious that he will never fully be a God. So this song is showing that he is in way over his head on his adventure and that he will not be able to follow through with what he wanted to do.
It's Hard To Say Goodbye by Michael Ortega is a song done by the piano. It displays the last of Gilgamesh, when he realizes that he will not be able to live forever and he is part of mankind. This song shows how sad and disappointed he was but that he can't do anything to change it anymore. He failed at his "tests" of becoming immortal and this is his realization that he is going to die.