Tobi

, at the beginning posing as in the Akatsuki, formerly appeared to be Zetsu's subordinate. Madara, as Tobi, became a full Akatsuki member after Sasori's death. He later wore Sasori's ring having recovered it after his death and took his place as Deidara's partner. After Deidara's death, he revealed his real name and that he had been the one giving Pain orders, making him the true leader of the Akatsuki. Only Pain, Konan, Zetsu, Itachi Uchiha, and Kisame Hoshigaki (who recognized him as the former Mizukage) know his true identity. He is one of five people who can use the Mangekyo Sharingan, the other four being his clanmates Izuna Uchiha, Itachi Uchiha, and Sasuke Uchiha, along with an unrelated Kakashi Hatake.

Background
According to Madara, eighty years ago when shinobi were battling as individual clans, not as villages, among a countless number of them, two clans emerged as the strongest: the Uchiha clan and the Senju clan. Madara was also the first to activate the Mangekyo Sharingan. He had a younger brother named Izuna who was equal to him in every way and also awakened the Mangekyo Sharingan. Together they ruled over the Uchiha clan, with Madara taking the role as leader. But eventually Madara went blind, due to side effects of the Mangekyo Sharingan. During the final fight of Itachi and Sasuke, it is revealed that Madara took away his brothers eyes which killed his brother. Contrarily to what many believed, Madara claimed that his younger brother gave him the eyes voluntarily to protect the Uchiha clan. At some point in Madara's early life, by the decision of the entire Uchiha clan except for him, he formed an alliance with the Senju clan, Hashirama Senju's clan, and together with its leader, the future First Hokage, Madara founded Konohagakure.

However, when Hashirama was chosen to be the First Hokage of Konoha, Madara feared that the Uchiha clan would lose supremacy and he sought the help of the Uchiha in his challenge for leadership. The Uchiha clan, however, refused, believing he was greedy. None of the Uchiha would help Madara, and he decided to leave the village. Feeling hurt and betrayed, he came back and wanted revenge against Konoha which led to a legendary battle at the Valley of the End against Hashirama. During the battle, Madara used his Mangekyo Sharingan to take control of the Nine-Tailed Demon Fox and used it in a desperate attempt to kill Hashirama. Madara, however, was ultimately defeated and was presumed by most to have died after the battle. Madara fled, and was never seen or heard of again out in the public for decades. To commemorate the battle, two statues, one of Madara and the other of the Hashirama, were carved into the earth around the waterfall. It is for this reason that Naruto Uzumaki and Sasuke's fight at that location was noted to be ironic. Madara created the criminal organization known as the Akatsuki to look over problems. He hid behind the shadows and placed Pain as the figure-head leader, with Madara giving Pain orders from the background. Besides Pain, the only members who are shown knowing Madara's position as the true leader are Konan, Itachi, Zetsu, and Kisame. Itachi and Minato believes it was Madara himself that controlled the demon fox to attack Konoha, though Madara denies this, saying that the demon fox was a natural disaster. Nevertheless, when he came to destroy the entire village of Konoha in revenge, he met up with Itachi, who had already been assigned his mission to kill his clan. Itachi successfully talked Madara into only killing the Uchiha clan as long as he left the rest of the village alone. Madara also taught Itachi about the Mangekyo Sharingan, helping him by teaching him how to unlock its true power. After Itachi killed off the Uchiha clan because of orders from Konoha, Madara let Itachi into Akatsuki for unknown reasons. Itachi refers to Madara today as "a pathetic shell of his former self, no longer worthy of being called the greatest Uchiha." It has also been recently revealed that at some point after being presumably killed, Madara took the role of Mizukage.

Personality
Madara sometimes exhibits a very calm and serious personality and at other times he exhibits a playful disposition, especially when in the disguise of Tobi. He speaks with less formal diction, such as not using honorifics, and shows typically "villainous" arrogance. Despite this apparent arrogance, he is not above complimenting the abilities of Sasuke Uchiha and Naruto Uzumaki, if only for the interest of Sasuke's Sharingan and Naruto's Tailed-Beast. Despite his villainous personality, during the first wars he wanted to protect the Uchiha clan and knew that the wars would eventually extinguish it, which is why, when the entire clan wanted it, he agreed on the peace treaty with the Senju clan.

Tobi
To keep in Akatsuki's shadow, Madara eventually took on the disguise of Tobi and was placed within Akatsuki as Zetsu's subordinate. As Tobi, Madara wears an orange mask, with swirls focused around the right eye, that covers his entire face outside of his right eye. Before wearing the swirl mask, Madara wore a similar mask, with markings across it which resembled the Hidden Mist Village's ANBU mask, covering his entire face but the right eye. However, the mask does not bear the symbol of the Hidden Mist Village. Furthermore, Tobi has several bolts or pins present on the arms of his uniform, obscured by his Akatsuki cloak. While acting as Tobi, unlike others within Akatsuki, Tobi is carefree and goofy, but Madara uses a very formal and correct manner of speech. While Tobi greatly respects his other members, referring to Deidara as "senpai", most of the other members tend to get easily annoyed by him. Deidara, who believes all within Akatsuki should be serious and calm, is not pleased with Tobi's childish personality, and frequently attacks the latter in a comedic fashion when annoyed. Kisame and Zetsu, on the other hand, somewhat appreciate Tobi's ability to brighten up a gloomy organization such as theirs. As Tobi, Madara has not been seen wearing a forehead protector, probably to conceal his identity, though he already has a mask covering his forehead, so this could also be why it is not visible. Although, it stands to reason that since Madara hates Konoha, he probably refuses to wear the headband anyway, like Orochimaru and Sasuke.

Rescue Gaara arc
Madara is first introduced as Tobi alongside Zetsu collecting the rings of Deidara and Sasori. While Sasori's ring is collected, Deidara, who managed to live after his confrontation with Kakashi, appears and reclaims his own ring. After annoying Deidara three times, Deidara responds by comically choking Tobi with his feet. Using Sasori's ring, Tobi manages to join Akatsuki, though Zetsu claims it isn't as easy as collecting the ring (Zetsu appears to be hiding Tobi's true identity to Deidara by mentioning this).

Three-Tails Arrival arc
Tobi, Deidara's new partner, find that their next mission is to capture the Three-Tailed Beast. Along the way, Tobi continues to annoy Deidara to no end. Deidara also shows an interest in what Tobi looks like behind his mask in a scene somewhat similar to episode 101 when team 7 tries to peak under Kakashi's mask. However even when they stop for a bite to eat, Deidara is ultimately angered by Tobi to the point of blasting Tobi across the forest with one of his bombs.

Three-Tails Capture
Tobi, who by now has successfully joined Akatsuki, is sent to collect the Three-Tailed Beast with Deidara. After Deidara reveals that this is Tobi's mission, Tobi, panicking, is seen only running away from the Three-Tails in a comic fashion. After the battle, which goes mostly unwitnessed (to further add mystery to Tobi's identity), Tobi triumphantly claims to have defeated Three-Tails in a single blow, though Deidara disagrees. Tobi later falls asleep atop the Three-Tails after making another cheeky comment, much to the anger of Deidara, who "wakes him up" by detonating a clay bomb next to him.

Hunt for Itachi Uchiha arc
Tobi is seen following Deidara, who is chasing Sasuke Uchiha, and eventually join Deidara's battle with Sasuke, though he does little by laying mines for him and serving as a distraction. When Deidara prepares to use C4, Deidara orders Tobi to flee, although escaping C4, Tobi is later shown getting killed by Deidara's final explosion, the CO.

It is later revealed, however, that Tobi lived, as he is seen with Pain and Konan in Amegakure just a few minutes after Deidara's death. Tobi is shown to temporarily discard his fake persona and reveals himself as Madara Uchiha, the benefactor of the Akatsuki. Madara then gives Pain, the apparent leader of the Akatsuki, the order of personally capturing Naruto Uzumaki. After his order, Madara travels to the Valley of the End on his own statue as Tobi, and while resting there, comments that Sasuke's Sharingan is growing more powerful.

Madara reappears as Tobi to stop Kakashi's tracking team from searching for Itachi (later changed into finding Sasuke), and phases through all attacks the group sends, even a full-powered Rasengan from Naruto and a full ranged attack from Shino even after completely covered in the latter's bugs. Tobi continues to fight the 8-Man Squad until Zetsu arrives to tell him that Itachi has died, which was no surprise to Madara. Before leaving, his Sharingan was spotted by Kakashi. Madara and Zetsu then arrive at Itachi's battlefield, to retrieve the two brothers, before the 8-Man Squad caught up to them. Off in a cave somewhere, Sasuke is startled to see Madara, who says he gave him some first-aid, and that Itachi had removed the seal. Madara then claims to know the truth about Itachi as he removes his mask revealing a glimpse of his Sharingan. Upon seeing Madara's true face, Sasuke's left eye begins to wield a black-flame and burns Madara, which causes the latter to distance himself. Madara realizes that Itachi has given Sasuke Amaterasu and the rest of his eye techniques, as a fail-safe in case Sasuke ever met him.

He then continues by saying that Sasuke had to question him, calling it his mission and duty. He also narrates to Sasuke about the origins of Konoha. He then begins to tell Sasuke the truth about Itachi. He reveals that Itachi risked all to protect the shinobi world, Konoha, and most of all, his little brother. Upon hearing Madara, Sasuke shows his persistence into thinking that what the former said is a lie. In response, Madara proves to Sasuke that if he was lying, the latter would have been dead by now. Coming to an epiphany, Sasuke deeply regrets killing Itachi and reforms Team Snake by changing the team's name into Team Hawk, whose new purpose is to destoy Konoha.

After the formation of Team Hawk, Madara removes his mask before Kisame. In response, Kisame recognizes him as the Mizukage, stating that he feels better knowing "you're the one who's pulling the strings". Kisame states that "when the planning began, Madara officially allied Akatsuki with them for their goal to destroy Konoha". After Kisame's speech, Madara states that they will use the Tailed Beasts to destroy Konoha and will require Team Hawk to capture the Eight-Tailed Beast. Afterward, Madara meets with Zetsu to discuss the fate of the fallen Akatsuki members, and more importantly, how Madara now has Sasuke. He displays some gratitude to Deidara and to the fallen Akatsuki members who agreed to join (Sasori, Hidan and Kakuzu), stating that they wouldn't have gotten this far without them.

Sasuke & The Eight-Tailed Beast arc
Madara is seen with Kisame and Zetsu, all of whom appear as holograms, sealing the Eight-Tails (which Sasuke successfully captured) in another hidden Akatsuki hideout. In a surprised twist of events, the host popped, reverting back into a tentacle of the Eight-Tailed beast. Madara is shown to remain silent, as Kisame comments that Sasuke has been fooled in the latter's attempt to capture the jinchūriki.

Abilities
Most of Madara's abilities are still unknown. However, he has been regarded as the strongest Uchiha to ever live ( by pressumably mastering all of his clan’s jutsu and skills). Like Itachi, Madara has been regarded as incredibly gifted as a shinobi. He has also been noted to have been born with a particularly powerful chakra, which he states is the reason for his "stubborn refusal to die". His chakra is too strong even for the Uchiha clan, who were known for having exceptionally strong chakra. Even the Nine-Tailed Fox mentions that Madara's chakra is even more sinister than its own.

He was armed with a giant fan during the time of Konoha's founding, fitting with his clan's name, which means "paper fan". Madara’s prowess in battle has earned him a reputation rivaling that of the First Hokage, as he is referred to by Itachi as an "invincible immortal", yet is also referred to as currently "a defeated dog". Madara also appears to have immense strength, as he was able to stop a slash from Suigetsu's giant sword with a single arm.

Mangekyo Sharingan
During Itachi's fight with Sasuke, it was revealed that Madara Uchiha and his younger brother, Izuna, were the first members of the Uchiha to activate the Mangekyo Sharingan, and used its power to take over the clan. After implanting his brother's eyes into his own body, Madara then awakened a new "eternal" Mangekyo Sharingan. The Eternal Mangeyko Sharingan was a combination of his own and Izuna's Mangekyo Sharingan. It gave him access and mastery to his clans’s most consequential jutsus, including a “final and ultimate jutsu” as Itachi stated, along with untold amounts of power without the risk of losing his eyesight. Madara's knowledge and mastery of this powerful Dojutsu allowed him to fight on par with Hashirama and it gave him the power to forcibly subdue the Nine-Tailed Fox. It was also thanks to Madara's knowledge of this Dojutsu that Itachi learned how to properly use his Mangekyo Sharingan.

Teleportation
Madara shows the ability to recover from debilitating or even fatal blows. After being slashed across the midsection by Sasuke's sword, he collapses, only to stand up again a few seconds later and complain about the speed of the attack, and later when Naruto hits him in the back with a Rasengan. The attacks literally phase through him, avoiding damage.

Madara also shows the ability to travel long distances within relatively short time-spans, escaping the final explosion created by Deidara and reappearing in Amegakure and the Valley of the End all within a very short period. It is speculated by Kakashi that he uses space/time Ninjutsu to instantly send himself or even parts of his body to different locations or some sort of void and instantly bring them back. During his fight with Naruto and the rest of the 8-Man Squad, Madara demonstrates a mastery of space/time Ninjutsu that, as speculated by Kakashi, surpassed even the Fourth Hokage. With it, he has been able to take Naruto's head-on, fully powered Rasengan by having it phase right through him, as well as being able to escape Shino's bugs (even though they completely covered him).

Speed
As Tobi, Madara displays incredible speed. This trait alone gains him a lot of praise from other members of Akatsuki. Kisame also comments "he is a good runner.". He is seen to be fast enough to outrun the Three-Tails while the beast was quickly swimming after him.

Nine-Tails Control
Madara is also the only known wielder of the technique of summoning the Nine-Tailed Fox, a being so powerful that it almost laid waste to Konoha until the Fourth Hokage stopped it. As of date, Madara has been the only person capable of taming the tailed-beast (with the use of his Mangekyo Sharingan), which was said to only come where human malice collects and festers.

Past Speculation
Before Tobi is revealed to be Madara Uchiha, several fans hypothesized that he could be Obito Uchiha, as his only shown eye was the opposite of the eye that was inserted in Kakashi. Obito's eye replaced Kakashi's destroyed left eye in the manga-exclusive Kakashi Gaiden. They also have similar hair styles as well as the same blood type, "0". Also, they both act in the same goofy way. Half of Zetsu claims Tobi to be a good boy while Obito was a good boy. The spelling of Obito was also similar to Tobi, creating the fan reference of ObiTobi, or Tobito.

Other speculations note a similarity between Pain's multiple bodies and the bodies summoned by Orochimaru's Summoning: Impure World Resurrection. The speculation is that Obito could have been reanimated or also had Madara's spirit implanted within him. This speculation is inherently flawed though, as neither of the techniques noted by fans were ever shown or meant to be used in the ways that fans speculated.

Fans also speculate that Madara could also be Danzo as many physical characteristics of Madara/Tobi and Danzo are similar. Tobi has bolts on the same arm that Danzo has covered up. They both share hair styles and have wrinkled faces. Danzo's right eye is covered by an eyepatch. Tobi's right eye is the eye that Tobi's mask reveals and is the same eye Madara has shown his Sharingan.

Trivia

 * Apparently, Madara and Konan are not on good terms with each other as he always questions Pain's abilities and she immediately scolds him for it despite him being their benefactor.
 * The phrase "Tobi is a good boy" has proven to be very popular among the Naruto community. Although not said by Tobi himself (Zetsu's white half actually uttered the phrase to his black half after stating Tobi's intentions of joining Akatsuki wasn't so simple to accomplish), many have found the comment to have hilarious effect and as such, Tobi is depicted as a carefree child or a good natured character in many fan-made art and videos on Youtube while incorporating the phrase. Many have altered the phrase, after Tobi revealing that he's Madara, saying "Tobi is a Bad Boy".
 * Because the Raikage had requested for a summit of the five Kages, some speculate that Madara might appear at the summit. This is highly unlikely though, as Madara was a former Mizukage.
 * Despite Tobi and Madara being the same person in the third Databook they have different character profiles.
 * Madara has stated that Akatsuki didn't have the power to destroy Konoha. However, Pain was able to destroy most of the village, meaning that Madara might not know of Pain's true strength.
 * Since Madara was once the Mizukage, it is possible he was the Mizukage that Zabuza Momochi tried to kill in his failed coup d'etat.
 * Madara and Orochimaru are extremely powerful ninja who share certain things in common: they both desired to be Hokage but were rejected, tried in failure to destroy Konoha, went on to become a leader of another village and an interest in Itachi Uchiha later transferred to Sasuke Uchiha.
 * It is also speculated that Madara might be able to see some parts in the future, as he knew Sasuke would beat Itachi, and also that Sasuke would change the name of his group from "Team Snake" to "Team Hawk".
 * Madara's choice of weapon is a scythe with a war fan attached to it, as shown in the single frame depicting his fight against the First Hokage. This wields the Uchiha symbol on it and Madara doesn't use it at the moment.
 * Some fans still believe that Obito is Tobi for Obito could be the reincarnation of Madara and share a body with him.
 * Why Madara chose the name Tobi as a cover is currently unknown. A possibility is that the name derives from the brother of his former rival Tobirama Senju.
 * There seems to be some dispute on who actually created the "Akatsuki." While Itachi states in chapter 386 that Madara created Akatsuki and "hid (himself) in its shadow", Pain has recently told Naruto in chapter 436 that he created "Akatsuki" to "break the chain of hatred."
 * As Tobi, Madara is shown to have incredible speed. He was fast enough to earn praise from both Zetsu and Kisame for it.
 * The reason behind Madara's choice to act like a total idiot as "Tobi" is still unknown.
 * can be translated as "jump", while can be translated as "spots".
 * The Fourth Hokage claims that Madara is using Pein, and that he was the one controlling the Nine Tailed Fox when it attacked the village.