Zero Tails [Reibi] was a demon who appeared in Naruto Shippuden the Movie: Bonds. The Zero Tails was created by the dark thoughts and feelings of all the oppressed people. The creature creates a large amount of Dark Chakra that the Land of Sky used to power themselves and their weapons with. In the movie, the Zero Tails was sealed within Amaru. Eventually, Amaru couldn't control the beast anymore and it was released and attacked Naruto and friends. However, Naruto was able to help Amaru suppress the demon.
Eventually, however, Shinno fused with the demon instead, resulting in a insanely powerful version of it. In this new form, the Zero Tails was even stronger, as it took both Sasuke and Naruto to defeat it. Eventually, however, they were able to defeat it using a Tornado Rasengan. In its basic form, the Zero Tails can grow fists, create a large mouth, and extend/grow tendrils which it uses to stab its foe. In its ultimate form, the Zero Tails can create unlimited amounts of hands, all of which grab hold of the foe and drain their character. It can also use these hands to form a shield.