Hattori Hanzō (服部 半蔵, c. 1542 – November 4, 1596) or Second Hanzō, nicknamed Oni no Hanzō (鬼の半蔵, Demon Hanzō), was a famous Ninja of the Sengoku era, who served the Tokugawa clan as a ninja, credited with saving the life of Tokugawa Ieyasu and then helping him to become the ruler of united Japan. He is often a subject of varied portrayal in modern popular culture. Hanzō was known as an expert tactician and a master of sword fighting.