Xion

Xion (シオン, Shion) is a new member introduced in Kingdom Hearts 358/2 Days. She was first shown in trailers and demonstrations for 358/2 Days. She was first believed to have been Naminé, but Nomura later informed the press that it was a different character. Like Roxas, she wields the Keyblade in its Kingdom Key form, and uses a fighting style identical to Roxas'. She forges a friendship with Roxas and Axel during her time in the Organization. Later in the game, it is revealed that she is a replica created from Sora's memories, and is thus not technically a member of Organization XIII or even a real Nobody. Her name is derived from the name "No. i", where i represents an imaginary number, foreshadowing her non-existence in Organization XIII. The character's voice actors are Risa Uchida in Japanese and Alyson Stoner in English

Roxas

Roxas (ロクサス, Rokusasu) is the Nobody of Sora. Xemnas finds him in Twilight Town and gives him the epithet, "Key of Destiny" (めぐりあう鍵, Meguriau Kagi, lit. "Serendipitous Key"), using him to gather hearts for the Organization. Roxas first appeared in "Another Side, Another Story", a bonus trailer found in Kingdom Hearts, and is mentioned in several cryptic comments made by other Organization members in Chain of Memories. Prior to the release of Kingdom Hearts II, screenshots and video showed Roxas without an Organization coat, in a black outfit with a white jacket and light brown pants. Roxas controls Samurai Nobodies and initially uses the Kingdom Key, the primary form of the Keyblade, in battle. He can manipulate the power of light to augment his physical attacks and create energy-based melee weapons and barriers. After Xion's sacrifice, Roxas gains the ability to wield two Keyblades, which the form of the Oblivion and Oathkeeper, symbolizing Sora's bond to Riku and Kairi. Roxas' time in Organization XIII is further explored in Kingdom Hearts 358/2 Days, where he acts as the main protagonist and player character. The character's voice actors are Kōki Uchiyama and Jesse McCartney in Japanese and English respectively.

Larxene

Larxene (ラクシーヌ, Rakushīnu), also known as the "Savage Nymph" (非情の妖姫, Hijō no Yōki, lit. "Callous Vixen"), was first introduced in Kingdom Hearts: Chain of Memories where she conspired with Marluxia to overthrow Organization XIII. Larxene wields a set of knives called Foudre (エクレール, Ekurēru, lit. "Éclair"), the French word for lightning, and uses the power of electricity to fight. The character was first voiced by Rieko Katayama in Chain of Memories. Yuko Miyamura took over the role for the Japanese releases of Re:Chain of Memories and 358/2 Days, while Shanelle Workman provided her voice in the two titles' English releases.
She first meets Sora in Chain of Memories and helps manipulate his memories by causing him to remember Naminé's name. She then fights him and gives him new cards to access more areas of Castle Oblivion. After she discovers Axel's betrayal and sees that Marluxia's plans have fallen apart, she decides to reveal her and Marluxia's plans to Sora with the intention of killing him. However, Donald and Goofy arrive to assist Sora, and the three defeat Larxene, who fades into darkness. Larxene makes a minor appearance in 358/2 Days, reluctantly training Roxas before she leaves for Castle Oblivion.

Marluxia

Marluxia (マールーシャ, Mārūsha^?) is lord of Castle Oblivion and the main antagonist of Sora's story in Kingdom Hearts: Chain of Memories. Also known as the "Graceful Assassin" (優雅なる凶刃, Yūga-naru Kyōjin, lit. "Graceful Assassin's Blade"), he uses a scythe called Graceful Dahlia (優美なるダリア, Yūbinaru Daria) and has control over rose petals to attack. Tatsuya Kando provided simple battle expressions in the Japanese and English releases of Chain of Memories. Shūichi Ikeda took over voice acting for the Japanese releases of Re:Chain of Memories and 358/2 Days. Keith Ferguson provided the voice in the English releases.
In Chain of Memories, Marluxia lures Sora to Castle Oblivion so Naminé can manipulate Sora's memories as part of his plan to take over the Organization, giving Sora a set of cards allowing him to proceed through the castle. Marluxia assigns Axel to eliminate Vexen to prevent him from revealing the conspiracy to Sora. After kidnapping Naminé in the aftermath of Larxene's death, Marluxia is confronted by Axel, who attempts to kill Marluxia for conspiring against the Organization. However, Marluxia uses Naminé to have Sora fight Axel for him. After Axel's defeat, Marluxia orders Naminé to erase Sora's memories so he can rebuild Sora into his pawn, but she refuses. Marluxia engages Sora using an illusion of himself, but Sora finds the real Marluxia fused to a massive cloaked Nobody and defeats him. Marluxia makes a minor appearance in 358/2 Days, training Roxas before he leaves for Castle Oblivion.

Luxord

Luxord (ルクソード, Rukusōdo) is a Nobody also known as the "Gambler of Fate" (運命を賭す者, Unmei o Tosu Mono). He controls the Gambler Nobodies, can transform Sora into a card or a die and uses a deck of cards called "Fair Game" (フェアゲーム, Fea Gēmu) as offensive and defensive weapons. Luxord also has power over time, which he uses to force his opponents to play timed games. Luxord speaks formally and often suggests rhetorical questions. The character is voiced by Jouji Nakata in Japanese and Robin Atkin Downes in English.
His next appearance was in Kingdom Hearts II, where he reveals himself at Port Royal and revives the curse of the Aztec gold to create a Heartless, indirectly cursing Jack Sparrow in the process. Sora later frees Jack from the curse, but Luxord escapes without fighting Sora and his party. At the World That Never Was, Luxord traps Sora's companions in his cards, leaving Sora to fight alone in a game-like battle, but is defeated and fades into darkness, asking "Roxas" why he attacked him. Luxord appears 358/2 Days, where he assists Roxas in various missions on Wonderland. Like most of the surviving members, he does not know about the Replica Project and Xion's origin until late in the game. Shortly after, he laments his subordination to the Organization to Roxas.

Demyx

Demyx (デミックス, Demikkusu) is the Organization's reconnaissance agent who is also referred to as the "Melodious Nocturne" (夜想のしらべ, Yasō no Shirabe). He is a slacker who would rather play his sitar "Arpeggio" (アルペジオ, Arupejio) than go on missions, especially those that require him to perform physical labor. He is a smooth liar as he tricks Roxas into working in his place every time they are sent on missions together. Though he admits he is not much of a fighter, Demyx has power over water, using it to create duplicates of himself. He also has control over the Dancer Nobodies. Demyx is voiced by Kenichi Suzumura and Ryan O'Donohue in the Japanese and English versions of the series, respectively.
Soon after appearing in Kingdom Hearts II at Hollow Bastion with the other Organization XIII members, he is assigned to look over Sora's progress in the Organization's plan, much to his chagrin. Demyx confronts Sora in the Underworld of Olympus Coliseum, stealing a medallion called the Olympus Stone to protect him from the Underworld's energy-reducing curse. After attempting to talk to Roxas through Sora, Demyx pits him against his water copies, and leaves after losing. Demyx later crosses paths with the protagonists again at Hollow Bastion, and battles them after they enrage him by mocking his nature as a Nobody, but is defeated and fades into darkness. In his first chronological appearance in 358/2 Days, Demyx reluctantly participates in the missions Saix assigns to him out of fear of what Xemnas could do to him.

Axel

Axel (アクセル, Akuseru), the "Flurry of Dancing Flames" (おどる火の風, Odoru Hi no Kaze), is a Nobody introduced in Kingdom Hearts: Chain of Memories. His original self is named Lea (リア, Ria), and was originally friends with Isa before he became Saïx. Much like his original self, Axel wishes to achieve his own ideal of immortality by having everyone he comes in contact with remember him, saying the phrase "Got it memorized?" on multiple occasions. Entrusted to deal with Organization traitors, Axel controls the Assassin Nobodies, and fights with a pair of "chakrams" called "Eternal Flames" (エターナルフレイム, Etānaru Fureimu) and fire manipulation. Axel is assigned to Castle Oblivion during the events of Kingdom Hearts: Chain of Memories, pretending to join with Larxene and Marluxia in their plan to seize control of the Organization. He kills Vexen to gain their trust, but finds himself confronting Sora while Marluxia uses Namine as a shield. Nomura designed Axel based on a similar concept as Reno from Final Fantasy VII; Nomura wanted to see what it would be like to have a similar character in a different role and world. The character is voiced by Keiji Fujiwara in the Japanese release of the games, while Quinton Flynn provided the voice for English releases.
During Kingdom Hearts II, Axel is ordered by the Organization to capture their lost member Roxas who was also his friend. Roxas refuses to return with him and ends defeating him before merging with Sora. Axel later begins acting on his own and kidnaps Kairi, but Saïx takes her under Xemnas's orders. Axel later finds Sora in a pathway to the World That Never Was and chooses to fight the Nobodies with him. Outnumbered, Axel performs a suicide attack to save Sora, and using the last of his strength to open the entrance to the World That Never Was. When asked what he was trying to do, Axel admits he wanted to see Roxas.
While acting as Roxas's mentor in the first half of 358/2 Days, he befriends the new Nobody as well as the other new member, Xion, eventually learning that Xion is an imperfect replica of Sora created by Xemnas. Upon learning the truth, Axel reluctantly hides it from Roxas while being forced in hunting down Xion when she attempts to leave the Organization. After Roxas abandons the Organization, Axel recaptures Xion, refusing to let her sacrifice herself.
Axel makes a cameo in the secret ending of Kingdom Hearts Birth By Sleep on Twilight Town's clock tower along with Roxas and Xion. The scene is explored in Kingdom Hearts coded, revealing that Axel is connected to Sora's heart. In Kingdom Hearts 3D: Dream Drop Distance, Axel's death is shown to have revived Lea, who spends the game searching for Braig and Isa. In doing so, he becomes an ally of Sora and his companions, rescuing Sora from the newly formed Organization. By the end of the game, Lea reveals himself to have become a Keyblade Wielder