if i was going to say it was someone we have seen or heard of before madaras brother makes the most since based on age skills and knowledge, but the clan barried him and i am sure the 1st would have known about him still being alive. i dont think he is anyone we have seen i think madara met him when he left the village and after meeting him he made the plan that is going on now. then madara came back to the village to fight the 1st. but there is just to much unknown about tobi he is a great medical ninja he has both uchia and senju dna in him via cells transplant or hereditary and his skills and knowledge

Izuna was burried, but he could've easily transported out, seeing how Tobi has that ability, so Izuna is still a valid candidate. The first may have some sensory like ability that Naruto has (Sage mode, though it is still unconfirmed), but I don't think that it'll reach into another dimension, which Tobi can open up (shown in the Kage arc where Sasuke is transported into that other dimension). Though Tobi could just be another person who we've never seen before.

wombat3476 u are one of the few people who actually sound like they know what they are talkin about

maybe it's kabuto's father.... juz guessing

i would give u that if izuna is tobi he could have teleported. but with what. he had no eyes? as far as we know it that tech is a sharingun tech at least as far as we know it.

thank u mrmcdonald i read alot!!!! u should try leafninja.com they got some good stuff on there

Well it isn't entirely confirmed that the transportation jutsu is a sharingan technique, which was stated by Almightywood. I guess it was just assumed that it is a sharingan technique seeing how the transportation jutsus animation appear near the eyes.

http://www.fandom.com/fandom/naruto/blogs/662/to bis-st-jutsu/

It shouldn't be a surprise madara is dead. The fact that he was summoned by edo tensei doesn't change anything because you already get a sense he is dead. Tobi mentions how he wanted nagato to use rinne tensei jutsu on him. Doesn't that mean tobi is dead? So, why can't tobi still be Madara. Real madara knows about the moon plan so same intention as tobi. Plus madara has rinnegan and first hokage cell, with that it is possible tobi is still madara or part of him.

na tobi isnt because u have to summon ur soul no soul not alive. plus tobi said for him not on him. if tobi jutsu wasnt a sharingun tech why would he tell kakashi it wouldnt work on him

how do you know if madara doesn't have his soul? What if he has many souls or split his soul. That Doesn't mean someone can't exist in the real world if there dead. Part of their soul can reside on the other side, while his other half in the real world. Madara with rinnegan can do anything. He has limitless possibilites. He can probably coexist in two different worlds or different times.

But my best guess is tobi is creation of madara. Madara or someone else transferred part of madara into their creation. Tobi resemble more of madara than any other uchiha mentioned such as his evil intentions, abilities and what he says. His space/time jutsu could be result of how he was created rather than his sharingan, but doesn't mean we can be sure tobi is someone else when he can be simply a creation or STILL be madara.

I don't think Madara is one being. He is an entity that brings chaos into the shinobi world.