Darkwater was the founder and mayor of Junktown.
He was an American soldier who found himself without an allegiance after the nuclear holocaust devastated the planet. He founded Junktown shortly after the war. Instead of building on the ruins of an old town, he thought it would be better to begin from the ground up. As the name of the town suggests, it was built out of random pieces of junk, mostly from wrecked cars.
Darkwater is mentioned only in Fallout.