SPOILER WARNING – this article contains speculation about future events in the final novel of the Harry Potter series, “Harry Potter and the Deathly Hallows”. Do not continue reading if you are not interested in such speculation.
Rowling, after a fashion, has not only told us who will live, but also told us how Harry can "vanquish" Voldemort without becoming a murderer.
The following characters from the stories have been wished "Happy Birthday" on JKR's site (alphabetcial order):
Now, by itself that's just a list of characters, but we know it's an incomplete list. What else is interesting, is that it's not just a list of good guys, because the list includes Draco, Dudley, and Snape. And it includes no character who we know is dead: Albus Dumbledore is not mentioned, nor is Sirius Black, nor Cedric Diggory, nor Moaning Myrtle nor any of the ghosts, nor Peeves. It becomes pretty clear that if you die, you're not on the list. That means that if Jo has wished you "Happy Birthday", it means you will see them through the end of the books.
This also means we need to consider significant characters who are presently (as of the end of HBP) alive, yet are not wished "Happy Birthday" by Ms. Rowling:
Peter Pettigrew (Wormtail)
This does not mean that all these people will die, of course; some are not important to the story (note that I did not mention characters who have graduated or who have no reason to appear in DH). But it does give one a few ideas.
Perhaps the most interesting thing, is that both Harry Potter and Tom Riddle are wished "Happy Birthday", which seems strange until you notice that "Lord Voldemort" is not mentioned. As we have seen in the cases of Severus Snape and Draco Malfoy, it is entirely possible to be nasty and mean without going all the way to evil beyond redemption, and Tom Riddle might be described the same way - he became evil when he became Voldemort. So, and this is a stretch I admit, what if Harry finds a way to "vanquish the Dark Lord" in accordance with the Prophecy, but "the other" which is mentioned in the prophecy is - really - the battle between Tom Riddle and Lord Voldemort?
You see, the prophecy line, "neither can live while the other survives" has bothered me for some time, because both Harry and Voldy have been around together for years - sure they have had clashes and are headed for a showdown, but I notice that Riddle ends where Voldemort begins. And if that means what I think it does, that is also what Dumbledore was trying to do instead of kill Voldemort: Dumbledore tried, and Harry will succeed, in changing Voldemort back to Tom Riddle. That is the 'fate worse than death' from Voldemort's point-of-view, it would keep Harry from being a murderer, and oh yes, it would explain why Harry's blood in Voldemort was so significant - just as Riddle-to-Voldemort was a gradual process, so too is the return trip. I don't know the details, but Jo has