Hanzō

also known as was a legendary ninja who was the former leader of Amegakure. He was very security-conscious, being guarded twenty-four hours a day and having anyone who wanted to see him thoroughly searched. He became famous around the time of the Second Great Ninja War. Little is known of his abilities aside from his riding on the head of a giant salamander (presumably a summon), but he was so powerful that he with his summon fought off all three Sannin. After their battle, he was so impressed with their strength that he decided to leave them if they agreed to accept the title of Konoha's ; This makes him responsible for the naming of the trio's title. Being capable of defeating all the three Sannin head-on, Hanzo is easily a kage-level ninja. His power was such that Jiraiya expressed intense shock upon hearing that Hanzo had been defeated by Pain.

Hanzo's insecurities later got the better of him when a group of ninja, lead by Yahiko, Nagato, and Konan began a quest to end war through unorthodox means. He viewed these ninja as a threat to his power and sought to get rid of them. He then teamed up with the ANBU Root's leader Danzo to kill the group's leader Yahiko in a treacherous manner. He was later single-handedly killed by Pain (under unknown circumstances). The hatred that Nagato had for him for causing Yahiko's death was so severe that he conducted a systematic genocide on anybody even remotely associated with Hanzo (with the exception of Danzo, who somehow escaped the carnage).

Abilities
While Hanzo's abilities as ninja are mostly unknown, Hanzo was easily one of the strongest ninja of his time. His trademark ability was the summoning of a giant salamander to aid him in battle. When battling alongside his salamander, Hanzo was powerful enough to fight and eventually overpower all three Sannin. During his attempt to kill Nagato, Hanzo demonstrated impressive skill for trap-oriented techniques as he anticipated Nagato attacking him and had several exploding tags prepared.

Trivia

 * Hanzō may have been named after a famous real-life samurai and possible ninja Hattori Hanzō.
 * Hanzō's eyes are very similar to Kakuzu's.
 * Although he defeated the 3 sannin, it should be noted that they were not as skilled back at hanzo's time then they are at the current time period, i.e. orochimaru hadn't yet delved into forbidden jutsu, so the 3 ninja were probably high-jounin level during their bout with hanzo.