One of my favorite super-short sci-fi stories had a man floating in space, unable to die, cursing the deal he made with the Devil. By this time, all energy and all matter had been absorbed into black holes, and he simply floated in space, hoping to even see a black hole wink out of existence (from Hawking radiation) to break his boredom.
I can no longer find the story, but it was great.
The Weapons Shop of Ishar, A. E. van Vogt
maybe?