Good place to start to look might be with the Sumerians.
A bunch of their stuff depicts giants as their kings.
I forget where I read or heard it but it was something about how they thought they were suppose to be hybrids.
Yes thanks , I am familiar with it.
I guess I should have been more clear in my previous post to Quix that the main reason the Sumerians came to mind was their language . Their language was very different for the area , not Semitic or Indo in origin.
As to the Sumerians, The Epic of Gilgamesh!