Hanzo of the Salamander

Hanzo of the Salamander was the former leader of Amegakure. He was extremely powerful and feared by many. During the Second Shinobi World War he squared off with Jiraiya, Tsunade, and Orochimaru, defeating all three of them. But, due to their ability to survive his onslaught, he let them live and gave them the title of the "Legendary Three Ninja." Hanzo was also responsible for Yahiko's death, and crippling Nagato. Later, however, Hanzo was killed by Nagato using his six paths of Pain.
In the past Hanzo seemed to have been a man of moral character, but somewhere along the way he sacrificed his principles for personal gain.
As a young boy, a poisonous black salamander died in Hanzo's village. After its death, Hanzo had the salamander's poison sack implanted in his abdomen, to give him unique poison abilities. He wears the gas mask to keep those around him from inhaling his poison breath, as it would kill them.