In Short: The really muscular naked blue guy from Watchmen
In Long: A normal man, exposed to radiation by accident one day at work at an army base. His body was torn apart, literally. But he was able to rebuild himself piece by piece. He is America's greatest weapon because he has a high level of radiation surrounding him, and can disintegrate his enemies on contact. He wore clothes twice in the movie "Watchmen". All the other times, he was naked, and nobody seemed to mind, or even notice. Just see the movie, it explains alot of stuff.
Dr Manhattan: "The existence of human life is a highly overrated phenomenon"