I've read peoples' ideas that Harry himself is a Horcrux and that he will create a Horcrux for himself in order to destroy the one inside of him and still remain alive. I cannot stress enough how much I disagree with this theory. I firmly believe that Harry is NOT a Horcrux. He cannot defeat Voldemort if his soul is split and therefore will NOT create a Horcrux. Dumbledore said that "he [Voldemort] never paused to understand the incomparable power of a soul that is untarnished and whole." That being said, if Harry splits his soul, that "incomparable power" is infinitely weakened.
In order to create a Horcrux, an act of extreme treachery and hate must be commited- murder. Sure, Harry indeed hates Snape, and murderous thoughts will inevitably cross his mind, but ultimately, I feel that Harry cannot or will not perform the task of killing Snape (either because he finds information that will change his mind, or because he simply won't become a murderer out of free will). On top of that, to create a Horcrux, one needs to use complex Dark Magic. Harry is not a Dark wizard, and I do not think that he will go so low as to use it.
Also, the one thing that Harry has that gives him more power than Voldemort knows is that four-letter word associated with Cupid: love. Love is something that Harry can proudly say is in his blood, and willingly taking away someone's life (Voldemort the exception) would definitely weaken the love that is inside of him.
Furthermore, Harry cannot defeat Voldemort, even in the latter's mortal form, if he destroys himself, the alleged Horcrux. If Harry's mortal self is destroyed, all that would be left of himself is that of what Voldemort used to be when 'Avada Kedavra' backfired. So even if part of Harry's soul was preserved, he would be too weak, and thus useless, against Voldemort.
