Black Zetsu

Black Zetsu (黒ゼツ, Kuro-Zetsu) created from the will of Kaguya Ōtsutsuki to secure her revival, is the mastermind behind many of the events that shaped shinobi history. He is the Wicked Tongue of Satan.

Yggdrasil Island Arc
Black Zetsu was created by Kaguya Ōtsutsuki shortly before the Ten Tails was sealed as the Ten-Tails by her sons, Hagoromo and Hamura. It would later tempt Hagoromo's eldest son, Indra, to go to war with his younger brother, Asura. Over the centuries, it manipulated Indra's descendants, the Uchiha clan, as well as Asura's, the Senju clan, in an attempt awaken the Rinnegan in one of the brothers' reincarnations. To this end, it modified Hagoromo's tablet to claim that Infinite Tsukuyomi would be the Uchiha's salvation, among other things. It recorded many events in history for Kaguya, including Madara Uchiha and Hashirama Senju's last fight in the Valley of the End.

Birth of Ventus Arc
After a distraught Legacy about Paul Gekko, During the Fourth Shinobi World War, Black Zetsu was supposed to be a Fossil. He declared that he is in reality "the will of Kaguya". Following this declaration, Black Zetsu proceeded to revive Kaguya in Vandesdelca Musto Fende's place. Two incarnations of Black Zetsu once again re-emerge to absorb Ventus and Paul's chakra. While attached to their bodies, Black Zetsu shows and explains to them what he did to ensure Kaguya was revived. After he is completed, he attempts to return to Kaguya, but Paul Gekko and Ventus manage to regain control of their bodies and rip Black Zetsu off themselves, preventing him from absorbing any more chakra. He notes that Naruto and Sasuke are too rebellious, and that they can't do anything to Kaguya. Nonetheless the duo attack Kaguya and prove to be surprisingly effective in their coordinated strikes. It is then when Black Zetsu suggests to Kaguya that she separate the two in order to pick them off one by one. Kaguya complies with this by promptly sending to the Village. Kaguya decides to return to her Battle with Paul Gekko where she revives the Juubi from the Pickle Jar. The Juubi, Kagya and the Black Demon prepares the Bijuu Bomb like it was 67 Years Ago to strike Paul Gekko. Unfortunately Simon uses his Magic to try a fend Altairis off, but it proves to be too much for him. He collapses and though Erza tries to keep his eyes open, he proclaims his love for her and dies, remembering Erza when she was young and leaving the world with a smile. Black Zetsu launches a tirade not only about Naruto's futile efforts, but what he believes to be Obito's wasted life; and though Obito agrees to this, Zetsu's words do nothing but infuriate the touring Paul Gekko. Simon dies, leading Black Zetsu to comment that Obito was a cockroach for having last so long rather than a regular insect. Natsu is furious to hear the Black Zetsu's Words and punches Kaguya, Cutting her Left Arm to be killed by the Hands of Paul Kiske.