He is one of the many humans that fell victim to Kaguya's Infinite Tsukuyomi in the past and was transformed into a White Zetsu. Unlike White Zetsu, Tobi is very unique in the sense that he has a spiral pattern across his entire body.
Tobi was fully white and could be easily distinguished by the spiral-pattern that stretches all over his body, ending in a circular eye-hole.
Obito went by the name Tobi after resurfacing prior to the Fourth Shinobi World War. They have similar personalities, and they are also actually voiced by the same voice actor in the English version of the anime. On top of that, Obito wears a mask before the Fourth Shinobi World War that resembles Tobi's face.
While Nagato became the Akatsuki leader and recruited powerful missing-nin for their cause, Obito took on the alias of "Tobi", and changed his personality around members to conceal his identity.
Tobi's true identity is: Obito Uchiha. He pretends to be Madara because he does not want to reveal his true identity because he should already be dead. that he can pretend to be someone else (Tobi), but once everyone calls him Madara, he changes his attitude to serious.
Obito's hate for the Uchiha was simply a result of Madara's animosity towards the clan, as they had betrayed him long ago and had decided to side with the Senju-led government.
One common theory that fans came up with was that his change in behavior was due to split personality disorder. In the Naruto series, Tobi could have been the manifestation of the fun and goofy side of Obito, which he didn't really get to showcase in the series. He has always been a serious person with big dreams.
The answer to this is very simple, Kakashi had absolutely no idea that the techinique Tobi was using was kamui he only realised it in the War Arc and after that, it didn't take him too long to conclude that the masked man who was said to be Madara was actually Obito.
Sasuke was completely aware that someone assisted Itachi in annihilating the Uchiha Clan, and that was revealed to be: Uchiha Obito, while he was impersonating Madara. Although Itachi did think that Obito was the real Madara.
Though, Kakashi never realized until Tobi started dropping hints in the 4th War face-off.
Obito Uchiha gained the Rinnegan after Nagato Uzumaki died. Strangely, having both eyes was too much for his body to handle, so he only implanted one Rinnegan into himself. Nonetheless, Obito's usage of this eye was quite great.
[7][8]Madara's mask at the time he met Itachi.To keep in Akatsuki's shadow, Madara eventually took on the disguise of Tobi, giving orders to Pain in secret. He wears an orange, swirl-patterned mask that reveals only his right eye.
He was powerful enough to fight both Kinkaku and Ginkaku at once, which is certainly a testament to his abilities. However, Tobirama was definitely weaker than his brother, who openly admitted to being inferior to Obito Uchiha. There's no denying that Tobirama was no match for the Uchiha.
During the Kakashi Gaiden, Obito is 13 years old before meeting what seems to be a grisly end. However, in Naruto: Shippuden, Tobi reveals his true identity as a 31-year-old Obito Uchiha.
Tobi was originally one of the various humans transformed into a White Zetsu after Kaguya had originally released her Infinite Tsukuyomi.
Obito became a villain after witnessing the death of Rin at the hands of Kakashi. Convinced that the world of dreams was the way to go forward, Obito did everything in his power to help Madara achieve his goal.
The manga finally reveals the the fake “Madara's” identity: Obito. Why this makes sense: 1) The names “Tobi” and “Obito” are very similar.
In conclusion, Obito Uchiha would defeat Itachi Uchiha when comparing the two characters in their strongest forms. Obito has one of the strongest, if not the strongest, Sage Mode in the series and has enough chakra reserve to beat Itachi.
Ultimately, the battle is a stalemate and a true testament to Obito's strength. Kakashi is one of the strongest characters by the end of the manga and the show, but Obito is definitely his equal.
Madara was much stronger than Obito to begin with, and the fact that his version of the Ten-tails was perfect made him even stronger. When compared to Madara, Obito stands absolutely no chance.
In Masashi Kishimoto's original story, Kabuto claims that he could get a big enough sample of Jiraiya's DNA to reanimate him, but Obito (still masked at this point) says not to push his luck. In the anime, Kabuto simply says that he can't reanimate Jiraiya because his body is at the bottom of the sea.
Since Kakashi lost his Sharingan he isn't able to use Chidori anymore but he has incorporated several other techniques to replace it, such as Purple Lightning. In Naruto, Chidori is a very powerful Lightning Release technique that takes a heavy toll on the user's body and draws a lot of chakra.
Itachi wasn't strong, he was super smart. Obito feared his smartness. He knew Itachi would destroy any plan of obito as long as he's alive. Obito was not afraid of dying, he was just afraid of his plan getting ruined.
Tobi was afraid of Kabuto using Madara to fight him, not Madara himself.
Obito Uchiha, also known by his iconic alias, Tobi, as well as the Masked Man, is one of the main antagonists of the Naruto franchise. He is the true leader of Akatsuki and serves as a dark reflection of the titular hero Naruto Uzumaki.