Uchiha Madara

Madara Uchiha (うちはマダラ) was the leader of the Uchiha clan prior to and after the formation of Konohagakure. He also helped to found Konohagakure.
Before the era of ninja villages, Madara was the most gifted member of the Uchiha clan. Even by his clan's standards, Madara's chakra was unusually strong. He grew up constantly competing and training with his younger brother,Izuna Uchiha. In their efforts to surpass the other, each gained their own Mangekyō Sharingan. With the power of the Mangekyō the two brothers took control of the clan, with Madara as its leader.
Because of the never-ending series of battles of the time, Madara eventually began to suffer from overuse of the Mangekyō Sharingan, leaving him blind. In order to regain his sight he took Izuna's eyes for himself, granting him an "eternal" Mangekyō Sharingan with which he led the Uchiha clan to prosperity. While Itachi Uchiha would later go on to state that Madara took Izuna's eyes without his consent, it is unknown if this is actually true.
Over the years, the Uchiha had constantly fought with the equally powerful Senju clan and as such, Madara had an undying rivalry with Hashirama Senju, the leader of the Senju clan. To bring an end to the constant fighting, Hashirama approached the Uchiha with an offer of peace. Although Madara never wanted peace with the Senju, the rest of the Uchiha wished to end the fighting, and Madara had no choice but to accept. The Senju, the Uchiha, and all the clans they had conquered came together to form the village of Konohagakure. 
Decades later, a masked-individual known as Tobi began operating under Madara's name. Tobi is intimately familiar with Madara's history, sharing his animosity towards Konoha and the Senju and even going so far as to claim that Izuna willingly gave up his eyes. It is, therefore, difficult to say which actions were those of Tobi and which were those of the real Madara. At the very least, Madara is aware of Tobi's existence. This masked man is known to have manipulated the Fourth Mizukage, been the cause behind the Nine-Tails' attack on Konoha, participated in the Uchiha clan massacre, and taken a hand in creating and leading Akatsuki.

Personality


 As an Uchiha, Madara possesses an innate hatred against the Senju clan, in what is known as the Curse of Hatred, which dates back to the early days of the ninja world. This curse led him to oppose the truce fearing that his clan would be oppressed by them, and when Hashirama was selected to be Hokage instead of Madara, he defected from Konoha and attempted to attack the village. His animosity to Hashirama was particularly strong, going as far as to forbid Ōnoki from mentioning that name in front of him ever again.

Abilities


Madara is considered by many notable individuals to be one of the most gifted shinobi in history and the most powerful that has ever been produced within the Uchiha clan. He has been noted to have been born with particularly powerful chakra, which even the Nine-Tails claimed to be far more sinister than that of its own. 
The fact that he fought and survived numerous battles with Hashirama Senju, who was recognised as the strongest ninja in the world in his time, prior to their truce indicates that Madara was also one of the strongest ninja of his time. Madara is one of the only shinobi in history capable of summoning the Nine-Tailed Demon Fox, the other being Tobi. However, it's sealing inside Mito Uzumaki and later Naruto Uzumaki have left him unable to do so.