Hiruko (ヒルコ) was once a renowned shinobi from Sunagakure. After his death, he became one of Sasori's first human puppets and one of his favorites. As a puppet, Hiruko served as Sasori's "puppet armor," allowing Sasori to hide inside him. Sasori even dressed Hiruko in the Akatsuki robes, and he wore it so frequently that people came to recognize him only when he had it on.
Chiyo noted that Hiruko had changed since she last saw him twenty years ago. Despite all his attacks failing due to Chiyo's manipulation, Haruno Sakura ultimately destroyed the puppet.
(Source: Narutopedia)
