Three survivors, the ferryman still remains too.
And Battlin you can kill before the last dungeon, just cast a death bolt at him
...ah good old times
Edit: sadly though you couldn't resurrect anyone you killed from the armageddon spell. There wasn't that much freedom. Casting armageddon ended your game
Forgot about ferryman... But I'm not convinced he's alive to begin with.
In fairness while true the deathbolt thing was a bug, you weren't supposed to be able to kill that particular mobile... Just get to the point where it was deleted and replaced with it's mortal clone.
And now that I think about it your right. I was running around recently in a version (exult) where you could cast resurrect after Armageddon but I do distinctly recall not being able to in the original release and another version where you could resurrect after, but only NPC's you manually murdered before casting it...
...
Why were all the best RPG's buggy as hell?

Someone made a mod for oblivion which added a resurrection spell and switched off the immortal tag on all the NPC's. I thought was awesome but it was less then perfect.
Issues with how the game handled tagging characters as dead and cleaning up after them meant you had to virtually cast resurrect on them before they finished dying or they'd get up with broken AI and as soon as you or they area transitioned they'd cease to exist. :-/
Fingers crossed mod makers wind up with a bit more in the construction set for Skyrim.