No.12622421 ViewReplyOriginalReport
I believe that Tobi is Mandara Uchiha using the body of Obito.

*If you take off one "o" in "Obito" you can rearrange it into "Tobi"
*Their hair-style is exactly identical
*They each have only one Sharingan eye, their right one
*Tobi at the beginning had a playful and carefree personality much like Obito did in the Kakashi mini-series