In chapter 559 it is revealed that it could be another person and not Madara under the mask. Who do you think it is?

Wow! That's a great thing. You're updated. XD I've also just read that chapter. And I think the person under the mask is Sasuke, just because I can't think of any other person. XD

I think it's obito personally could be wrong lol

i think its uchiha shisui o3o

I get the wackiest ideas when it comes to Naruto so here me out! XD lol

So, we don't know what ever happened to Rin (Kakashi and Obito's partner), right?

So what if Tobi actually turns out to be a girl? Of coarse, she would have to use some wacko jutsu to change her voice and stuff.... and I am assuming that if Rin was able to plant an eye in Kakashi, that she would probably be able to plant one into herself.

And this is why I have to stop reading Naruto O_O it is the only manga that gives me these weird ideas

DON'T RUIN IT FOR ME..

also i think it is also obito..

The man behind the mask is Madara since Kisame recognized him as the Mizukage of the Bloody Mist and Kabuto's trump card is a zombie Madara probably the final product of one of Orochimaru's first experiments -since he liked to play around with different DNAs. Madara was believed to be dead so it's very possible and we also have Madara's (or Tobi's, however you prefer) shocked impression when Kabuto exposed him to his mysterious "coffin".

Karin. I dunno. xD

I'm not sure but my guess is that he's someone from mandara's time who's history will be revealed when he is exposed but, I'm not sure.

I think it "could" be Obito but since Kakashi was just a kid when Madara battled with Minato, I'm not so sure about it. It might also be a totally new character.