Quoting arthosvalhalla

Clearly, Summoning: Impure World Resurrection is a forbidden technique used to revive the dead from its state of prime. Also, some might come with another good argument but i would assume Tobi is not Madara since Muu as Kabuto answered he is assisting HIM while talking to Madara. Izuna is still a good candidate and a far second would be Shisui from MY opinion

Shisui's eyes were pulled out, so what would be the use of him? And also, i'm pretty sure that Shisui wouldnt be physically formed like the one we saw attack Minato. FOr those who dont understand, im saying that shisui woullda probablly be a at a young age. I had leads to Izuna, but now everything is complicated. As you can see in the earliest manga, madara easily went to Eiternal Mangenkyo, so how would Izuna have eyes like tobi if madara had eternal. Its quite obvious that Madara took his brother's eyes for eiternal. They also dont add any information about the rinnigan. We know that the rinnigan was supposedly "tobis in the first place". So look at the sequence. Tobi says rinnegan was his. Madara has rinnegan. Surely you must see the relationship guys. Something doesnt match up though. And its also obvious that Madara knows OF tobi. Who is "him". Who is TOBI? This question cannot simply be answered with supporting details. We have to wait for more information.

There's only one other person who could possibly share Madara's grand ambitions, and that's Izuna. The only person we've heard about Izuna from is Tobi, and Tobi is a lying bastard when it benefits him. Why not pose as his brother while he works to resurrect him? Surely the name Uchiha Madara is more feared than Uchiha Izuna. Itachi mentioned Izuna to Sasuke, but how does Itachi know?

Suppose Izuna transplanted sharingan into himself from someone. Suppose he transplanted Madara's rinnegan into Nagato, to breed him into the one to resurrect him after he had contained all the bijuu within gedo mazo. Surely, this was what Madara had planned. Izuna could also easily look like his brother using henge or physical modification, in the fashion of Tsunade or Orochimaru.

Tobi could still be Madara, as well. The technique Nagato used to clone Itachi and Kisame comes to mind, if not something like Muu's technique. Either of those account for Tobi being a "shell of my former self," as the Itachi and Kisame clones had ~30% of their normal power. We don't know the limitations of either of those techniques, so either is possible.

Quoting Powder119

Suppose Izuna transplanted sharingan into himself from someone. Suppose he transplanted Madara's rinnegan into Nagato, to breed him into the one to resurrect him after he had contained all the bijuu within gedo mazo. Surely, this was what Madara had planned. Izuna could also easily look like his brother using henge or physical modification, in the fashion of Tsunade or Orochimaru.


This also clouds my mind. Masashi kishimoto really had us on our toes for this one. Very exciting.

"Shisui's eyes were pulled out, so what would be the use of him?"

Eyes pulled out from an Uchiha and replaced with another has been an old old story. Age is what bothers me for the Shisui theory, so that is why it is a far second to Izuna, nevertheles a possibility

Don't forget that Shisui, as his dying wish, wanted to protect Konoha. For him to be Tobi is utterly laughable. Almost as laughable as Obito being Tobi.

Quoting Powder119

Don't forget that Shisui, as his dying wish, wanted to protect Konoha. For him to be Tobi is utterly laughable. Almost as laughable as Obito being Tobi.

Tobi's eye of the moon plan has a goal to cover the world in an "Infinite Tsukuyomi" (Mugen Tsukuyomi), thereby letting him control every living being, creating a world in which no war or crime occurred. Quite protective as it seems.

Shisui's age is undertermined but would probably be the same range of Minato (very arguable). There is a slim possiblity but still a possibility.

Obito is the same age range with Kakashi, impossible to be the same person who fought Minato back then.

although it may seem more likely to be Izuna, you have to think. Tobi told the kages the battle with Hashirama. The fact he has knowledge of the Mangekyou sharingan techniques, the history of the Uchiha/Senju, as well as Madara's battle with Hashirama means it cannot be Izuna, because he was dead before the battle happened and well. How would he remember how he was buried? Another aspect is that Tobi replaces limbs like nothing, as well as eyes. Remember all those sharingan's he had? But eh, just my opinion.
But the fact they refer to Tobi as "Him" means it cannot be Madara (Obviously) because wouldn't Muu and Kabuto say "you" or something similar?
However the one like that contradicts a lot of theories is Tobi's line "Nagato betrayed me, he was meant to use that technique on me"
and Madara's : "So it finally happened, It would appear that little brat Nagato managed to grow"
So think, how exactly does Madara know of Nagato? Why is Nagato mentioned to be from the Uzumaki clan?
I think the secret of the masked man has to do with that.

Everything we know about Izuna was a result of Tobi, with a side note from Itachi saying that Madara stole Izuna's eyes.

Tobi is deceitful. Nothing he says can be taken at face value. Example: he said the kyuubi's attack 16 years ago was a freak accident, when it was revealed by Kushina that it was Tobi who controlled the kyuubi.

As a side note to that, the kyuubi seemed to recognize Tobi ("You...!", which implies that Tobi is Madara, who controlled the kyuubi in the past.

I've supported Tobi being either Madara or Izuna in the blog I made (The resurrection of Madara), and strongly discredited any other candidates.

Shisui died to protect Konoha. Tobi was also downfallen when he saw that Danzo crushed Shisui's eye. Shisui cannot be Tobi.

Obito was too young, and applying Madara's ambitions to him makes absolutely no sense, as is the case with Shisui.

Izuna is the only other person that could share Madara's ambition, and thus, Tobi is possibly Izuna, since everything we know about Izuna is probably a lie.

Until there is definite proof of Shisui's age,he is still on my list of the possibilities.

Yes, Tobi was pretty pissed when Danzo destroyed that eye. How is he aware that Danzo had the eye in the first place? Itachi went to great lengths to ensure his Sharingan (or face)and Saskue's never meet.With his ultimate Genjutsu control he could have made Itachi (or anyone for that matter)believe anything. There is nothing that says he can't control more than one person at a time. Just like regular Genjutsu the more people that look into the eyes, the more got trapped.
No one is able to locate Shisui's body, and both of his eyes were supposedly taken, one by Itachi (which he destroyed) and the other by Danzo (which he destroyed). This doesn't eliminate him as he could have easily been given new eyes. Sasuke could also be under Genjutsu which Shisui could only pull-off (like taking control of 4th Mizukage).
Acting like a fool under the presence of Itachi when the whole group of Akatsuki is still intact and never giving a hint on his identity would might also mean that fake Madara really knows Itachi well because he doesn't want Itachi to notice this.I vaguely remember that Tobi was disguising because of Itachi's capability to kill him which would also contributes to knowing a lot of Itachi's as a bestfriend.
In addition, for Itachi to have so much respect with Shisui, Shisui must have been pretty much accomplished back then. Also taking into consideration that Itachi is like a "gifted child" that he hangs around people older than him bcoz of the ranking he has achieved at an early age.He could see Shisui as an older brother or uncle perhaps.
The grudge factor for Uchiha clan would also be there for Shisui, since a lot of people, including Uchiha people wants his powers, that would probably led t0 his ultimate plan of a scheme of letting Danzo forcefully take his eye and lending his eye to Itachi and leading to a fake suicide death. And leading to an ultimate plan of recovering his eyes back and controlling over the minds of all people.
A fake suicide death which would probably be supported by the reason why kabuto wasn't able to resurect Shisui in the first place (since Kabuto also wants the power of Shisui) bcoz he wasn't able to locate the body/DNA of Shisui, no one else did.

I have maintained for quite a while that the only two characters that I think Tobi could be are Madara and Kagami.

After the recent manga chapters, I'm pretty sure it is Madara.

I won't rule out Kagami as a possibility (I already have with all the other candidates), but I'm one step away from it.

It doesn't matter how Tobi acts around Itachi. Itachi would recognize his chakra with sharingan.