Xehanort

Master Xehanort is the original master of Ventus, the creator and master of Vanitas, and the original incarnation of Xehanort. He is a Keyblade Master and the main antagonist of Kingdom Hearts Birth by Sleep and over the Xehanort Saga, overall.

Kingdom Hearts Birth by Sleep
In his youth, Xehanort, who once lived on a beach, had dreams of leaving his home in search for something greater. At some point he found a way to depart his home world and was trained to be a Keyblade Master, eventually befriending Eraqus, another Keybearer. He was taught the ways of the Keyblade and showed the Mark of Mastery. However, though his Master forwarned him to wear armor when traveling to other worlds to protect himself from Darkness, Xehanort felt it presence and embraced it, abandoning his Master's teachings. Throughout his life, Xehanort traveled to many different worlds and obtained vast knowledge concerning Keyblade lore, the power of Light and Darkness, a detailed knowledge of the Heartless, the mysteries of the Keyblade War and Kingdom Hearts. Realizing the power unlocking the "heart of all worlds" would grant, Xehanort set his goal on finding a way to open the door to Kingdom Hearts.

By the time he discovered a way of opening that door, Master Xehanort had grown old, and realized that he must transfer his essence and knowledge to a "new vessel" in order to survive to see his plans reach fruition. To this end, he sought out an apprentice and found the boy Ventus, who he began training as a Keyblade wielder, and future component for the χ-blade, a legendary Keyblade capable of unlocking Kingdom Hearts, by pitting him against one of Eraqus's students of light once Ventus embraced Darkness, as well as his the after future vessel. To this end, Xehanort brought Ven to the Keyblade Graveyard and summoned Heartless for him to fight and awaken his darkness. However, Ven refused to allow Darkness to grip his heart and was knocked unconscious. Fed up with Ventus, Xehanort decided he was too weak and a poor candidate, prompting him to instead use only him for the first part of his ultimate plan. Using his Keyblade, Xehanort extracted the Darkness in Ventus's heart and gave it the form of a boy, whom he named "Vanitas". Now that Ventus was two separate beings of pure light and pure darkness, they only need be made stronger to complete Xehanort's goal. Unfortunately, the process left Ven in a coma-like state with his broken heart of pure light slowly fading out. Master Xehanort (in a black coat) decided to leave Ven to die in a peaceful setting in his old home, Destiny Islands. To his master's surprise, Ventus's heart somehow survived and Xehanort realized the boy could still be of use. However, Ventus was still far too weak in comparison to Vanitas, for the two needed to be equal in power for the creation of the χ-blade. Xehanort brought his former apprentice to his old friend Master Eraqus to train Ven and make him stronger.

At this point, Master Xehanort set his eyes on one of Master Eraqus's apprentices: Terra, within whom he sensed the correct potential to be his new vessel as there was abundant Darkness in his heart. While in the Land of Departure, Master Xehanort sabotages the Mark of Mastery Exam taken by Terra and Aqua, causing Terra to fail, and later tells him that if he were to become a true Keyblade Master, he would have to embrace the darkness in his heart rather than slay it with Light. Shortly thereafter, Master Xehanort and Vanitas vanish to go on an apparent quest to find the Princesses of Heart for a back up plan.

During his travels, Master Xehanort manipulates Master Eraqus's apprentices (Terra, Aqua, and Ventus), who had been sent to find him and destroy the Unversed, a malicious species created as a side-effect of Vanitas's existence. He encounters Terra in the Keyblade Graveyard and puts his manipulative skills to the test, explaining the reason for his actions: He is trying to safeguard the light from the "demon" he unleashed. He then goes on to explain Vanitas's origins, how he was accidently created when Master Xehanort tried to save Ventus from succumbing to darkness by removing the darkness from him. Lying that Vanitas is responsible for the whole chaos of the Unversed, Master Xehanort pleads with Terra to help right this wrong by destroying Vanitas. Also, to make sure that his plans would go into action even if he should temporarily fall, Xehanort encountered Maleficent and told her all about the other worlds, Keyblades, and the Princesses of Heart. To make sure Ventus was not felled by the witch, Xehanort instructed Maleficent not to harm him and that Terra and Aqua would be useful in extracting the hearts of the seven maidens.

He next travels to Radiant Garden and strikes a bargain with Braig (who desires the Keyblade for himself), Master Xehanort stages his own capture and has Braig fight Terra, with Terra succumbing to the darkness and disfiguring Braig's face permanently. Master Xehanort tells Terra that he is a true Keyblade Master as he was able to channel the darkness. He then gives Terra an opportunity to be his pupil, claiming that they can do the worlds much greater good. Master Xehanort then pulls the final string, calling him by the name "Master Terra" and gaining the young man's trust.

Later on, Master Xehanort has Vanitas abduct Mickey Mouse as bait to lure Ventus to the Keyblade Graveyard, where he reveals to him the truth about his past, stating also that Master Eraqus knows about it. While Ven goes to see Eraqus, Xehanort tells Terra that Eraqus has gone mad and is about to destroy Ventus. Terra is tricked into defeating Master Eraqus in battle, allowing Xehanort to callously deliver the finishing blow to his former friend. Master Xehanort then tells Terra to go to the Keyblade Graveyard where he will see Aqua and Ventus for the last time before falling prey to the darkness. He then covers the Land of Departure in darkness, completely destroying the world and leaving nothing but the castle's remains, telling Terra he would not need a home where he is going.

Soon enough Terra, Aqua, and Ventus discover the truth and confront Master Xehanort and Vanitas at the Keyblade Graveyard (the remains of the legendary Keyblade War). There, Master Xehanort reveals to them his true plans to create the χ-blade and unlock Kingdom Hearts. In the ensuing battle, Master Xehanort freezes Ventus and has Vanitas knock Aqua out cold, while gleefully telling Terra that he is powerless to save them, causing Terra to lose control of his anger and succumb again to the darkness in his heart.

Terra uses the power of darkness to defeat the elderly Keyblade master, but Xehanort enacts his final scheme and uses his Keyblade to unlock his own heart and transfer it into Terra's body, prolonging his life and transforming him into the new Xehanort while his original body fades into darkness with a triumphant smile.

Blank Points
The hearts of Master Xehanort and Terra are (at the time) shown disputing over internal dominance within the new Xehanort. Despite Master Xehanort's insistence that he will soon incorporate Terra's heart into his own, Terra remains confident that he will win over Master Xehanort, who realizes that Terra is harboring the heart of Master Eraqus. Despite this, Master Xehanort shows no concern, and reveals to Terra that he has backup plans should his possession of Terra fail.

Kingdom Hearts 3D: Dream Drop Distance
Master Xehanort rerturns to life following Young Xehanort's defeat. It is then he reveals to the heroes that his Heartless and Nobody were acting together on his fail-safe plan. He tricked Maleficent into gathering the Princesses of Heart together so they could be eliminated and leave the worlds vulnearble to the darkness he would use to reorganize them. "Ansem" destroyed countless worlds for their hearts to build a Kingdom Hearts of darkness and possess Riku to make him the thriteenth vessel of his heart. Xemnas was to gather the hearts from Heartless to place into a Kingdom Hearts to place fragments of his own heart amongst the Organization's members.

However, Sora recused the princesses and sealed Kingdom Hearts, allowing a portion of the worlds that were destroyed to be reborn, "Ansem" was purged from Riku by the light of Kingdom Hearts, Riku's own efforts and the explosion of Ansem the Wise's machine. The members of Organization XIII either proved too weak for the process of being turned into clones or turned traitor/ destroyed; they were also unable to find any Nobodies to replace the fallen members. Only Braig and Isa proved able to be turned into clones; Braig had a fragement of Xehanort's heart implanted way back in "Birth By Sleep".

However, all this was expected; "Ansem" recurited Young Xehanort, his alternate younger self, and gave him the powers to travel through time and space to gather twelve different versions of himself to make up the thirteenth hearts of darkness needed to truly forge the X-blade when pitted against seven hearts of light. With Ansem and Xemnas hold Mickey and Riku down, Master Xehanort prepared to turn Sora into his final clone. However, the arrival of Lea, Donald, and Goofy forces Xehanort to retreat with his incomplete Organization, who each return to their respective points in time, and he challenges his opponents to clash with him when the time comes.

Quotes

 * All of this was decided. My twelve selves would welcome me here on this day, when I would return a complete person. It is the future that lies beyond my sight
 * Yes, he did. That dull, ordinary boy, a Keyblade wielder so unlike any I have ever seen. However, I have not abandoned my ambitions the seven guardians of light and the thirteen seekers of darkness.
 * Darkness can not be destroyed, it can only be channeled.
 * Ah, but destiny is never left to chance. I merely guided them to their proper place. The broken boy who failed to be the blade... the misguided master who sacrificed herself for a friend... and the feckless youth who became my new vessel.
 * Behold. These lifeless keys used to be full of power—united with the hearts of their masters. On this barren soil, Keyblades of light and darkness were locked in combat... as a great Keyblade War raged. Countless Keyblade wielders gave up their lives, all in search of one, ultimate key. And it will soon belong to me... χ-blade.
 * This world is just too small.
 * There, you see? An empty world, like a prison. I imagine you'll be right at home.
 * Still so blind... Then I will make you see. Come to the place where all Keyblade wielders leave their mark on fate—the Keyblade Graveyard! There you will watch your dear Ventus and Aqua meet their ends, and the last light within you will die!
 * But darkness did cover the world once,in legend.' We know so little about the Keyblade War—only that it was just the beginning. Amidst the crisis a precious light was found. It is a curious tale—and one worth exploring. They say ruin brings about creation. So what, then, would another Keyblade War bring? When the darkness falls, will we be found worthy of the precious light the legend speaks of? I must have these answers. The χ-blade needs to be forged, and with it, the door to the Keyblade War unlocked!
 * Then don't. You could be my pupil. Master Eraqus, you see, is so afraid of darkness, that he too, has succumbed—not to darkness, but to light. It shines so bright, he forgets that light begets darkness. And Aqua and Ventus, their lights shine too bright. It is only natural that they cast shadows on your heart. Eraqus... He is such a fool! Light and darkness, they are a balance—one that must always be maintained. Terra... you are the one who shows the true Mark of Mastery, but he refuses to see it. And I know why. It is because he fears you. Join me. You and I can do the worlds much greater good, by wielding light and darkness in equal shares.
 * But once again you have it all wrong, Eraqus. Darkness is a beginning, you see, not an end. At birth, every one of us emerges from darkness into a world of light, do we not?
 * Ah yes, so you are starting to realize... what you lost—oh, but not for good. You had to lose in order to find. Now it can all be yours again, if you only reach out and take it. Reclaim the part that left you. Clash with him! Pure light against pure darkness, to forge the ultimate key. The all-powerful χ-blade!
 * Yes, they were all my doing. I used the evil fairy to find seven pure lights for me, just as I prepared thirteen vessels to fill with pure darkness.
 * In ancient times, people believed that light was a gift from an unseen land by the name of Kingdom Hearts. But Kingdom Hearts was safeguard by its counterpart, the χ-blade. Warriors vied for that precious light, thus beginning the "Keyblade War". The violent clash shattered the χ-blade into twenty pieces— seven of light and thirteen of darkness. And the only real Kingdom Hearts was swallowed by the darkness, never to surface again.
 * We are out of time. Neither the union of light nor darkness has been achieved, and we must all return whence we came. But, the gathering of the seven and the thirteen is nigh. Let us finish this at the fated place, once your lights and my darknesses have joined together!

Gallery
Xehanort