Xehanort

Xehanort is a major antagonist of the Kingdom Hearts series, a former apprentice of Ansem the Wise, and the original persona of Ansem, Seeker of Darkness, and Xemnas. Xehanort was originally "born" as Terra-Xehanort, when his original incarnation, Master Xehanort forced his heart into the body of Terra; he became simply "Xehanort" when he seemingly lost his memories. He is the titular character and main antagonist of the Xehanort Saga, and has appeared in some shape or form in every game in the saga so far. Similar to the Organization XIII members, Xehanort's name contains the letter "X", along with anagrams for "No Heart" and "Another".

Kingdom Hearts II
The former apprentice of Ansem the Wise.

Even after becoming a Heartless, Xehanort persisted in his research of the doors and the heart of all worlds - all in the name of "Ansem", of course.

Meanwhile, his Nobody Xemnas had taken leadership of Organization XIII.

Between Kingdom Hearts Birth by Sleep and Kingdom Hearts
Following the loss of his memories, Xehanort ended up in the Radiant Garden, where he was found by Ansem the Wise, who took him in as his apprentice. With his supernatural abilities (stemming from being a former Keyblade Master), Xehanort quickly became Ansem's foremost apprentice. Eventually, Ansem began to worry about the darkness that lingers within the hearts of others and sought a way to stop it before it consumed his people. Ansem constructed a laboratory under his castle where he, Xehanort, and Ansem's five other assistants (Braig, Dilan, Even, Aeleus, and Ienzo) would conduct experiments on darkness.

Xehanort, who Ansem had by now come to fully trust as an apprentice and friend, offered to use himself in the experiments. Ansem also hoped to unlock Xehanort's memories in addition to uncovering a way to repress the darkness within hearts. Xehanort had other plans in mind though and decided to conduct his own experiments to go deeper into the research.

Xehanort, Braig, Dilan, Even, Aeleus, and Ienzo carried out their own experiments where they abducted countless people and locked them within the depths of the laboratory where Xehanort then conducted horrible experiments on the subjects. After using many test subjects, one set of experiments led to the collapse of their hearts. The subjects then went into unrecoverable conditions and were locked up in the dungeon of the castle. Eventually, Xehanort checked on the subjects and saw that they transformed into creatures of darkness, which he named "The Heartless" as they apparently lacked hearts. At this point, Xehanort had taken Ansem the Wise's name as his own and wrote his own report under this stolen name.

Xehanort then presented the Heartless with living and non-living samples; the Heartless only responded to the living. Xehanort witnessed the Heartless consume the living creatures and then multiply into more Heartless. Xehanort deduced that the Heartless seek the hearts of other things, which explains why they only react to living samples, in order to create more of their kind. Xehanort and his associates soon began to slowly accept the darkness, allowing them to have limited control over the Heartless.

They in turn began to look less and less human, a factor that Ansem himself realized. When Ansem learned that his apprentices continued with the research, he called them together and ordered for them to cease their efforts immediately, all the while questioning what was happening to his loyal apprentices. Xehanort, however, saw his master as a fool who had no understanding of research and kept the research operating.

After observing the behavior of the Heartless and their responses to living things, Xehanort took one of the Heartless aside and observed its behavior. The Heartless began to move throughout the castle until a door appeared which Xehanort was, somehow, able to open. Behind the door was a humongous mass of energy to which the Heartless reacted immensely. The opening of this door led to the collapse of the world's boundaries, which was seen in the form of a meteor shower. Xehanort eventually deduced that the door actually led to the heart of that world and that the opening of this door led to the collapse of the walls between worlds.

This allowed inter-dimensional travel as all the walls between worlds were now broken and eventually a visitor showed up named King Mickey. He had constructed a Gummi Ship, a spacecraft capable of breaking through world boundaries, out of materials from the meteors and used it to visit many different places in search of answers of recent events. Xehanort and Mickey met and had huge discussions in which Xehanort learned of the Keyblade, a mysterious weapon that Mickey himself possessed.

There were also legends that told of seven princesses with pure hearts and how they have a connection to this Keyblade. The Keyblade can also be wielded by many, as long as their hearts qualify, and it seems there is a legend of one Keyblade bearer who went on a journey of destiny to seal off the doors to other worlds. Since this was not in Xehanort's interest, he sought a way to find this weapon, which is ironic, given that his former self once wielded one, but was now lost. Mickey eventually met and befriended Ansem the Wise and the two of them exchanged theories and ideas in his office about what the Heartless were after. Ansem decided to resist the urge to test their theories while expressing deep remorse for his actions.

However, Ansem had no idea that Xehanort had gone further than he himself even dared. Xehanort entered the office during their discussion, asking Ansem's permission to test an experiment. Ansem forbade Xehanort to conduct it and told him to forget everything he learned from the research.

Even though Ansem had no further urge to research the darkness, the experiments led by Xehanort continued including the creation of a machine that created artificial Heartless, all of which were marked with an emblem created by Xehanort in order to differentiate them from the pure-bred Heartless. King Mickey suspected something odd about Xehanort and told Ansem to check his lab, collect all his data, and see if everything was under control.

Ansem did so and learned that Xehanort had taken his name as his own and wrote a detailed report. From the report, Ansem learned of the horrible torture inflicted on people by the inhumane experiments that Xehanort had done. Ansem ordered his apprentices to seal off the laboratory and cease their scheme for knowledge.

Ansem's apprentices did as he instructed them but Xehanort eventually banished Ansem to the Realm of Darkness and ravaged the world with Heartless. The Heartless under the command of Xehanort began spreading to other worlds and destroyed numerous ones in their mad search for hearts. One side effect of the destruction of so many worlds was the creation of Traverse Town, made up of the remains of the ruined worlds and populated by the few survivors of those said worlds. Xehanort then ordered for the seal on the laboratory to be broken and that a room that he called the "Chamber of Repose" be constructed. Once done, Xehanort often went in and spoke as if there was someone else in the room. It is later revealed that the room housed Aqua's armor, which Xehanort used to help gain further recollection about his past.

Around this time, Xehanort restored the Master Control Program and Sark to the Hollow Bastion OS.

Xehanort then abducted and sent Kairi, a resident of Radiant Garden, to the oceans of other worlds. The reason for this was because Xehanort thought Kairi had a connection to the Keyblade bearer, as she seemed to possess power comparable to that of a Princess of Heart, which is rumored to possess a connection to the Keyblade. He hoped to use her to find the Keyblade master and prevent him from sealing off the doors to other worlds.

Xehanort made the final pages of his report, which outlined his intentions as well as those of the Heartless. The Heartless seek to consume the hearts of all living things. However, they not only seek human hearts, but the hearts of the worlds themselves. Their ultimate goal is to collect enough hearts to form the biggest heart of all, the heart in which all that exist are evolved from: Kingdom Hearts. Xehanort decided to use the Heartless' instincts to make his own plans.

He would find Kingdom Hearts in order to gain ultimate power, control, and knowledge. Xehanort also learned that the creation of a Heartless can also lead to the creation of another creature called a Nobody, beings that are left over bodies of those whose hearts have been stolen away. They transform into an inhuman state and do not truly exist as they lack a heart to make them truly live.

Xehanort and the others eventually gave themselves to the darkness to gain the ability to control all Heartless and wield the powers of darkness. They lost their hearts in the process and they became powerful Nobodies. However, Xehanort was the only one to have both a human Heartless and a human Nobody, both possessing the memories and personality traits prior to their creations. Since they possessed strong hearts and wills, Xehanort and his followers (Braig, Dilan, Even, Aeleus, and Ienzo) were able to retain their human forms as Nobodies. Radiant Garden was almost completely destroyed, save for the castle and the mutated waterways, which had several modifications done to it by Xehanort and the other apprentices, and most of its people were wiped out while some (like Leon, Aerith, Yuffie, Cid, and Merlin) managed to escape to places like Traverse Town.

Kingdom Hearts II
While investigating Ansem the Wise's study within Radiant Garden, Sora, Donald and Goofy find a portrait of an unknown man who is later revealed to be Xehanort. After running into King Mickey, he explains that the man in the painting was the original body of "Ansem," the antagonist that the trio had defeated outside of the Door to Darkness. They find out that the true Ansem was not the one they had fought but the Heartless of the man in the portrait instead. At their return to Tron's computer, shown to them is an image of another unknown man, which the king identifies as the real Ansem. Later, after the battle of the 1000 Heartless, the trio encounters Xemnas, the Nobody of Xehanort who is the superior of Organization XIII.

In the World That Never Was, King Mickey encounters Ansem the Wise and learns that his goal is to destroy Xemnas' artificial Kingdom Hearts and exact revenge on Xehanort for stealing his name and pride. Ansem repeatedly used the name "Xehanort" to insultingly refer to Xemnas.

Signs of What's Next
Following the complete debugging of Jiminy's Journal, Yen Sid informs Mickey that Xehanort has been revived following the defeat of Ansem and Xemnas, and further warns him that more than one form of him may have returned.

Personality
As one of Ansem's apprentices, Xehanort appears to have had a very professional and no-nonsense attitude, shown by his determination in his studies. He appeared to be easily annoyed by Braig and was shown to be equally as interested in the darkness of hearts as his original incarnation. Xehanort appeared frustrated when Ansem forbade him from continuing his studies and experiments, and ultimately disobeyed his master. When speaking to Xemnas, Ansem the Wise refers to Xehanort as "foolish" and that any world of his "would be an empire of ignorance".

Appearance
Xehanort wore a white labcoat with rather loose sleeves that is partway zipped down. The coat also has pockets roughly where Xehanort's hips would be. He wears black boots that are identical to those worn by his Heartless, his Nobody, and the members of Organization XIII, with a white/silver lining along the top and an indentation on the sides. Underneath his coat, Xehanort wears a grey vest overtop a white collar shirt, along with a purple ascot around his neck. During this time, his hair is worn long, with two bangs framing his face. His hair also sports three backward-facing spikes, one at the top of his head, and one on either side, just above his ears. In addition his eyes have turned brown.

Trivia

 * In the Japanese version, Xehanort is voiced by Akio Ōtsuka, the son of Chikao Ōtsuka, the Japanese voice actor of Master Xehanort. Tetsuya Nomura cast Chikao for this particular reason.
 * Xehanort's two anagrams have been referenced in two separate ways:
 * When Xemnas visits the Chamber of Repose, his password in the computer is "Another".
 * In Kingdom Hearts Birth by Sleep Final Mix, there's a secret boss named "No Heart".