So... who is actually ALIVE from season one still?
Here's my count -
Jack Bauer - as we know he's the man, has appeared in all 6 seaons of course.
Milo Pressman - appeared in season 1, and now in season 6 as a replacement to Edgar Stiles.
Aaron Pierce - has appeared in all 6 seasons now.
Kim Bauer - some web forums say that she will appear later in Day 6 but apparently the actress has indicated that she does not appear in this season.
Mike Novik - the actor has not confirmed if he will return in Day 6 but he could still appear, since in the past Mike was typically introduced several episodes into the season. Maybe Martha will contact him if Charles Logan dies?
I'm pretty sure Aaron Pierce did not show up in Season 1. I would have to go back and check, but I don't think we saw him at all. Besides Jack, I think Tony, Michelle and the first President Palmer were the only ones in all five seasons before this one. Since they killed all of them off, Jack is the only character in all six seasons, unless you count the pictures on Wayne's desk of his brother.