Black Salamander

The was a creature native to Amegakure that was famous for the deadly poison its body produced. After its death, Hanzō during his childhood, had its venom sac implanted into his body, thus granting him the ability to create the same poison, as well as allowing him to develop a resistance to this particular poison. Due to the consequence that even by breathing he would release the toxin, Hanzō quickly became feared as.

Trivia

 * In the anime, the salamander was depicted as being brown, not black.