The Contrasting of Gilgamesh and Grendel

In the epic tale Beowulf the main villain is a monster called Grendel,in the story Grendel is making village life for the citizens under King Hrothgars reign. When Beowulf and Grendel meet in battle Grendel fights for his life and Boewulf actually had a reason for killing him. But in the epic tale  Gilgamesh the villain of this story is called Humbaba,and the Heroes only reasoning for killing him is that he wanted the trees he protected.