Over the years, fans have loved the characters from Kingdom Hearts. With the huge cast that was introduced in other Square Enix games and Disney films, this series has so many characters that it may be hard to keep track of them all. Many of the original characters were part of a group called Organization XIII. First introduced as antagonists in Chain of Memories, a lot of its members have since become friends with Sora, Riku, and the other Guardians of Light.

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Due to its convoluted plot that involves different worldlines, uses of time travel, and deep lore, it is easy for some fans to forget or miss some of the most important things in the games. Here are some things that fans should know about the group. Got it memorized?

10 Nobodies

Xemnas KH3

There are many types of enemies for players to fight in the series, with the two most common being heartless and nobodies. A nobody is a creature that comes from the body of someone with a strong heart after the two are separated. The members of Organization XIII are the strongest nobodies. Most of the original members were led to believe that they didn't have hearts and joined the group in order to obtain one. However, this was all a lie in order for the leaders of the group to accomplish their true goal.

9 Radiant Garden

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Xemnas, Xigbar, Xaldin, Vexen, Lexaeus, Zexion, Saix, and Axel were the original eight members of the group. Prior to becoming nobodies, they all lived in Radiant Garden and were apprentices of the world's ruler, a scientist named Ansem. After defeating their master, Xemnas and Xigbar convinced the other members to split themselves into a heartless and a nobody. Xehanort's heartless was so powerful that it appeared as a human and took Ansem's name. Xemnas would go on to create the organization.

8 Age Of Fairytales

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Demyx, Luxord, Marluxia, and Larxene were the next four members to join the group. Fans were shocked to find the original versions of Marluxia and Larxene, Lauriam and Elrena, in Union X, a game that takes place years before they were thought to be born.

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It was revealed in Kingdom Hearts III that Demyx and Luxord were also from this time period and that Xemnas chose them due to their forgotten past as keyblade wielders. As Union X is coming to an end, fans are hoping to find out how the four lost their keyblades and went into the future.

7 The World That Never Was

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Despite many of the members coming from Radiant Garden, the organization spent little time there after they became nobodies. The members lived at The World That Never Was, where they frequently had meetings and were assigned missions. The world consisted of a castle where the group spent their time and a city beneath it, inhabited by heartless and nobodies. Though most of the members spent their free time in this world, they had a second headquarters known as Castle Oblivion.

6 Traitors

Axel KH3

Sora and Riku first encountered Organization XIII at Castle Oblivion. After needing some of the untrustworthy members to leave, the leaders of the group sent Vexen, Lexaeus, Zexion, Axel, Marluxia, and Larxene to the castle. Axel was specifically sent to check if there were any traitors. When he found out that Marluxia and Larxene had planned on replacing Xemnas, Axel waited until the moment was right to destroy those in his way. He was the only member to return to the organization and would later betray the group himself, along with a few of the other original members.

5 A Forgotten Victory

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Due to their defeat in Kingdom Hearts III, players may have forgotten that Organization XIII had won their battle in a previous timeline. They could have fought against the Guardians of Light or the Princesses of Heart. As the Guardians were much stronger and wanted to protect the Princesses, they decided to be the ones to go into battle. However, the heartless defeated them before the battle could begin. Though it wasn't shown in the game, this would have resulted in Organization XIII defeating the Princesses. Not having anyone powerful enough to stop him, Xehanort would succeed in his goal.

4 Subject X

Axel and Saix

Prior to defeating Ansem and creating the organization, the apprentices helped their king with his experiments. One such experiment was known as Subject X, a young girl who couldn't remember her past. Isa and Lea snuck into Hollow Bastion and became friends with her. Wanting to help their new friend, they became apprentices themselves and would shortly lose their hearts. However, they never found her after that. Other members of the group were also trying to locate the girl. Though little is known about her, she was very important to them and fans suspect that she is Skuld from Union X. She may end up playing an important role in the next saga.

3 Replica Program

Kingdom Hearts 3 Data Battle Replica Riku

The Replica Program was another experiment in the series. Two of Organization XIII's members, Xion and Riku Replica, were the best results of the experiment and came as close to a person as possible, even being able to wield their own keyblades. Xion was introduced in 358/2 Days as Roxas and Axel's other best friend. Unlike most of the characters in the series, she was created by Tomoco Kanemaki rather than Tetsuya Nomura.

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Riku Replica was introduced in Chain of Memories and was split into two beings. One replica helped the real Riku in Kingdom Hearts III while the other joined the organization.

2 True Goal

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Despite being the main antagonist of the first saga in the series, Master Xehanort's plan to use Organization XIII and recreate the Keyblade War wasn't for evil purposes. He was actually hoping to rebuild the world and bring an end to the darkness. When he was young, four of his closest friends died and he went on a journey to other worlds, deciding that he needed to use the darkness in order to defeat it. However, when he faced against the Guardians, he realized that the world had changed from what he believed for so long and gave the X-Blade to Sora. Though he didn't accomplish what he had planned for years, he did help somebody else in their goal.

1 Pawns In Their Own Game

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Even though he appeared as one of the most loyal members of Organization XIII, Xigbar always seemed as if he knew more than he should have. Fans believed that there was more than meets the eye but were shocked to find out that the clever little sneak was actually Master Luxu. In the Age of Fairytales, Luxu was told to take his master's keyblade and a mysterious box. He hid the box and passed his keyblade down to his apprentice, which would eventually be passed down to Xehanort. He possessed other people and kept his eye on the weapon until the time was right. The Master of Masters had also inspired Xehanort during his travels when he was young, using him from the very beginning. What the Master of Masters and Luxu are really after remains a mystery that fans cannot wait to learn.

NEXT: Kingdom Hearts: 10 Things You Didn't Know About Sora