Is Tobi really Uchiha Madara?
: Apparently, yes. It has been said so in Naruto manga. The first time is back in Chapter 364, Volume 40, page 18, in which the person whom we originally knew as Tobi claimed that he has Uchiha Madara’s power. Later on it was much more apparent, in which in Chapter 396, the person that introduced himself to Sasuke claimed that he and Sasuke have met before as enemies (when Sasuke fight Deidara, so obviously he was referring to Tobi), and at the same time claimed himself as a “living and breathing Uchiha”.