Madara Uchiha (うちはマダラ, Uchiha Madara), who posed as Tobi (トビ) when first introduced, is a founder of Konohagakure and Akatsuki, and the former leader of the Uchiha clan. When he joined 晓组织 as Tobi (replacing Sasori), he was partnered with Deidara, revealing himself as Madara after Deidara's death. He was once the Mizukage of Kirigakure, although it is unknown when.
Decades before the start of the series, Madara grew up in constant competition with his younger brother, Izuna Uchiha, who were both known as the most gifted members of their clan. Their competition led to both gaining the Mangekyo Sharingan, and, with it, they were able to take control of the Uchiha clan, Madara 表演 as its leader. Even 由 his clan's standards, Madara's chakra was unusually strong. Under his leadership, the clan conquered all they came across, but, over time, he began to lose his sight because of the Mangekyo Sharingan. To regain his vision, he took his brother's eyes (an act Madara 说 his brother had consented to), allowing him to continue to lead the Uchiha to prosperity.
In the years that followed, the Uchiha constantly clashed with the equally powerful Senju clan. To bring an end to the constant fighting, the leader of the Senju, Hashirama Senju, approached Madara with an offering of peace. Although Madara never wanted peace with the Senju, the rest of the Uchiha wanted to end the fighting, and Madara had no choice but to go along with their decision. The Senju, the Uchiha, and all the clans they had conquered came together to form the village of Konohagakure. Against Madara's wishes, the villagers selected Hashirama as the village's First Hokage. Madara feared that Hashirama would oppress the Uchiha, and tried to rally support for challenging his leadership. Rather than help him, however, the Uchiha turned their backs on him, believing his only motive was greed.
Abandoned 由 his clan, Madara left the village so that he could return to challenge Hashirama in battle. They fought at the site that would someday be called the Valley of the End, where, although Madara called upon the Nine-Tailed Demon Fox, he was defeated, and was believed to have died. Madara faded into memory, and, in time, would found 晓组织 and become Kirigakure's Mizukage.
Twelve years before the start of the series, the demon 狐狸 attacked Konoha. Although Madara denied having had any involvement in the attack, Itachi Uchiha and Minato Namikaze 说 that the demon 狐狸 was under Madara's control at the time. A few years later, he infiltrated Konoha to try and rekindle the flames of war. He was found 由 Itachi first, who convinced Madara to spare the village in exchange for helping to wipe out the Uchiha clan for deserting him decades earlier. Madara complied, training Itachi and providing assistance. Itachi never truly trusted Madara, however, and kept an eye on him for the rest of his life.
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. When he trained Itachi, he wore a slightly different mask with black swirl-like patterns on it, and his hair was cut a little shorter. His hair is cut down completely from the days of Konoha's founding, and he wears a uniform consisting of a number of bolts and pins, which is usually concealed 由 his 晓组织 cloak.
While 表演 as Tobi, he is carefree and goofy, something that annoys most of the other members. Deidara, who believed all within 晓组织 should be serious and calm, was not pleased with Tobi's childish personality, and frequently attacked the latter in a comedic fashion when annoyed. Apparently, Madara is very committed to keeping his identity secret, as he has been seen keeping up his goofy appearance even when no-one was around (at least during the anime's filler arc). Kisame and Zetsu, on the other hand, somewhat appreciate Tobi's ability to brighten up a gloomy organization such as theirs.
Madara exhibits a very calm and serious personality. He speaks with less formal diction, such as not using honorifics, and shows typically "villainous" arrogance. He spoke down to Pain (going so far as to refer to him as a "minion") and has great faith in his own abilities, only 表演 polite to Sasuke Uchiha. He will abandon his normal personality in favor of the Tobi personality when the situation calls for it, as he did when distracting a group of Konoha ninja.
Madara has shown great ability in manipulating others to do his work for him. Minato believed that he was using Pain's ideology against him in order to control him. He similarly befriended Sasuke in order to get him to 加入 晓组织 由 telling him about Itachi's past, even though he has an apparent interest in Sasuke and his abilities. While Akatsuki's goal to gain the tailed beasts is believed 由 most of the members to be a step in gaining control over the world, Madara implied that the real reason is to restore his Sharingan's power.