Tobi (トビ), whose real name is Obito Uchiha (うちは オビト Uchiha Obito ), is the real leader of Akatsuki and the main antagonist of the entire series. He was originally Kakashi Hatake's teammate who gave him his Sharingan before his presumed death in the Third Great Ninja War. In reality, he was saved by Madara Uchiha who eventually took him as his apprentice to continue his work after he died when the youth witnessed Kakashi kill their teammate Rin caused by the actions of the ninja villages' conduct. Obito, having served a behind-the-scenes role throughout the first half Part II and causing most of the tragic events prior to the series that include the deaths of Naruto's parents. Other than using his right Sharingan to utilize Kamui in a fashion that made it seem he is intangible and teleport over great distances, Obito can use Wood Style attacks as he possess Hashirama's blood.
As Tobi, Obito joins the Akatsuki as Sasori's carefree replacement to oversee the Eye of the Moon Plan. After his partner Deidara dies in a suicidal bid to kill Sasuke Uchiha, Tobi starts taking a special interest in Sasuke's development up to Itachi Uchiha's death while conspiring the Akatsuki. After Nagato's death, deciding to completely assume the identity of Madara as he lost the means to revive him, Tobi reveals his mentor's Eye of the Moon Plan to the Kage to become host to a resurrected Ten-Tails to cast an eternal illusion called the Infinite Tsukuyomi (無限月読 Mugen Tsukuyomi ), bringing all life under his command. After the Kage refuse to surrender to him, Tobi declares the Fourth Great Ninja War and ends up forming a reluctant alliance with Kabuto Yakushi who blackmailed him with a reanimated Madara. Tobi retrieves Nagato's Rinnegan, replacing his left Sharingan, and uses it to convert the reanimated corpses of the captured Jchuriki into his personal Paths of Pain to use the captured Tailed Beasts' power through them. During the ensuing war, Madara is revealed and Tobi's true identity as Obito is exposed. Regardless, as the Ten Tails is revived while he and Madara control it, Obito made personal attacks on Naruto's friends to break his spirit before Hinata rekindled it and gave their side the advantage. After losing control of the Ten Tails, Obito ends up taking Kakashi to the dimension tied to Kamui where the two would fight as Obito reveals his true reasons for aiding Madara. Mortally wounded by Kakashi, Obito returns to reality where he is nearly sacrificed by Madara to restore the latter back to life until Madara's control over Obito is halted by the Allied Shinobi Forces, resulting in Obito becoming the Ten Tails Jinchuriki himself.
Tobi was Kishimoto's favorite Akatsuki character at the time to draw, due to his simple mask. In the Japanese anime, Obito is voiced by Naoya Uchida while his Tobi persona is voiced by Wataru Takagi. In his youth, he is voiced by Sōsuke Komori. In the English anime, Obito is voiced by Neil Kaplan with Michael Yurchak voicing his Tobi persona. Nolan North does Obito's voice in the video games while his younger self is voiced by Vic Mignogna.