So everyone has there own theory of who Tobi is but there one that really sounds believe able to me, the theory that Tobi is an Uzumaki. Uzumakiz live very looong lives and this might explain why Tobi lived throught the creation of Konoha to now. Uzumakies can handle tough strains on the body that's why all the nine tails jinchuricis were uzumakis and Tobi is confident he can handle the ten tails in him... Hm makes you think right. Now this other fact isn't as important but I'll still say it lol tobis mask looks like a whirlpool and that was the symbols of the uzumaki clan. The Uzumaki clan has senju in them so this explains why Tobi can use izanagi. So with all this being said I have a feeling that Tobi is an uzumaki.
Lol oh man, I just checked other websites were you
can read the Ch. and they either say you were the
third sage of the six paths or you were the the
third of the the six paths. So which is the right