Vigoor

"Enough of this, your insignificant life ends here."

- Vigoor

Vigoor (神聖皇帝ヴィゴル Shinsei Kotei Vigoru ), later reborn as the "Holy Vigoor Emperor", is the true main antagonist of Ninja Gaiden, Ninja Gaiden Black, and Ninja Gaiden Sigma.

Past
Vigoor was born from the fear and hatred that came to exist at the beginning of the universe. He became ancestor of all fiends and began devouring the world, unleashing undiluted chaos upon the world. However, Vigoor was eventually opposed by the 13 Dragon Gods in a battle that lasted aeons before he was finally beaten. But he was far from undefeated and Vigoor would take many opportunities to terrorize creation, albeit indirectly, such as his corruption of the youngest Dragon God into the Dark Dragon and the birth of the fiends from his body. However, Vigoor finally returned personally in the form of the "Holy Vigoor Emperor" and having built his namesake imperial cult known as the "Holy Vigoor Empire", his disciples who would be infused with his essence. It is unclear exactly where the Emperor came from but he did come to found a large empire dedicated to Vigoor on the spot where the Dark Dragon had been corrupted eons before. The fiends would find a home in this "kingdom", where they and Vigoor were worshipped fanatically. The Emperor waited for his chance to fulfill the prophecy of Vigoor's return, that said he would plunge the world into chaos yet again.

Ninja Gaiden
The Emperor eventually learned the location of the Dark Dragon Blade from the Dark Disciple and quickly sent his Greater Fiend servant, Doku, to retrieve it for him. He succeeded, razing the Hayabusa village in the process, and Ryu Hayabusa came after him to retrieve the blade and have revenge. However the Emperor planned for this, sending his forces against the ninja, knowing they would die as this would feed the Dark Dragon Blade. His power grew, causing the dark influence of Vigoor to spread until finally the Dark Dragon Blade was unsealed. The Emperor drew on its power to become a true incarnation of Vigoor, casing all reality to fall apart and summoning huge hordes of fiends. Eventually, Ryu faced off against Vigoor himself and managed to actually defeat his first form using the True Dragon Sword.Enraged, Vigoor emerged from the lava he had fallen into in a far more demonic form and attacked Ryu again. But he was again defeated and destroyed, freeing Ryu of the fiend curse that was on him.

Ninja Gaiden Dragon Sword
However, the fiend goddesses, Ishtaros and Nicchae, sought to bring back the Vigoor Emperor so as to begin the age of fiends again using the Dark Dragonstones. Ishtaros would end up slain by Ryu but her body was charged with energy from the stones which Nicchae used to resurrect the Emperor in his form as Vigoor's reincarnation. However the Dark Dragon was suddenly revived from Ishtaros' body, draining the power from the Emperor and making him degenerate to his demonic form. Ryu took him on and destroyed him yet again.

Powers and Abilities
Vigoor is a being of incredible power, given that he is a powerful deity, able to bend reality's laws and warp the world into chaos with ease. The Vigoor Emperor possessed his own supernatural powers before being transformed into Vigoor incarnate, but after unsealing the Dark Dragon Blade fully, he obtained all of Vigoor's power. Vigoor can also transform other beings into fiends and unleash various powerful attacks, such as energy beams.

Trivia

 * While it is unclear who exactly the Vigoor Emperor is, there are several theories such as he is Vigoor's reincarnation or a human transformed by Vigoor to be his servant, similar to Dagra Dai.
 * The Emperor's Palace looks normal at first glance, but upside down, it is shown to be a demonic skull castle.