Which one?
Most were probably covered by real-world Euhemerists, but I'll take a crack at Euhemerising the Judeo-Christian* God, focusing on the earlier parts of the Old Testament for reasons I will cover.
*Why is he called "the Judeo-Christian God"? Muslims must feel so left out.
This individual would have likely built an empire from a number of slaves he freed. After that, he would have built up a cult around himself, demanding that the former slaves abandon their other gods and devote themselves to him. He made a number of parables about people who displeased him, ranging from two orphans he let live in his garden until they stole fruit from one of the trees
[1], to how he flooded an entire province for failing to adhere to his laws, as well as those who followed them. He ruled for a while and then died. Genesis is a collection of these parables, corrupted and expanded through the generations, as the emperor's claims of godhood became accepted as fact; later books of the Bible were either histories, sermons of further preachers, or more parables that became accepted as fact.
Then the Christians came along...
Khan Noonien Singh (From Star Trek "Space Seed,"
The Wrath of Khan, and/or
Into Darkness)