Sora (ソラ, Sora?) is the primary protagonist of the Kingdom Hearts series. Sora's weapon is the Keyblade. Though not the original wielder of the Keyblade, Sora was chosen over Riku because Sora chose light, while Riku opened himself to darkness.

At the beginning of the series, Sora is 14 years old and lives on Destiny Islands along with his two friends, Riku and Kairi. When their world is attacked by a group of corrupted hearts known as the Heartless, the three are separated. During the invasion, he obtains the Keyblade. Soon after, Sora meets Donald Duck and Goofy, who join him on his search for his friends. To blend in with the inhabitants of the various worlds they visit, the group's appearances are altered by either Donald's magic or, in Kingdom Hearts II, by Sora's magical clothes. Some examples include a dolphin-like merman and a brown lion cub. Sora later meets Riku on several occasions, but the two clash over saving Kairi. Riku is later possessed by Ansem, Xehanort's Heartless. After fighting him, Sora sacrifices himself to restore Kairi's heart to her body, and becomes a Heartless and creating his Nobody, Roxas. Soon after, he is brought back by Kairi. Sora, Donald, and Goofy then fight and defeat Ansem, and with the help of Riku and King Mickey on the other side, they seal the door to Kingdom Hearts.

Sora, Donald, and Goofy then resolve to find Riku and the King. While traveling they find a fortress known as Castle Oblivion. Upon entering, they begin to lose their memories and Sora's memories begin to be manipulated by the Organization that is controlling the castle. The Organization use Naminé to make Sora forget Kairi and replace his memories of Kairi with herself. Sora discovers the truth behind the events that have taken place and after defeating the Organization members, he meets with Naminé. She puts Sora, Donald, and Goofy to sleep for one year to restore his memories to their state prior to entering Castle Oblivion. The three awake a year later in Twilight Town and learn about the Nobodies and Organization XIII. Sora also obtains a new ability, "Drive Form", from the fairies Flora, Fauna, and Merryweather, which allows him to transform into more powerful forms and access to new abilities. Sora and the others begin their quest to confront Organization XIII and solve the mystery to why Sora is constantly being referred to as "Roxas". They eventually find King Mickey and Riku (rescue Kairi) who assist in fighting the organization's leader, Xemnas. Sora and Riku are separated from the others to fight Xemnas one last time. After defeating him they find their way back to Destiny Islands, where they are reunited with Kairi, Donald, Goofy and Mickey.

Kairi (カイリ, Kairi?) is a friend of Sora and Riku, and one of the seven "Princesses of Heart".She is originally a resident of Hollow Bastion, but she was sent to the Destiny Islands by Xehanort a few years before the events of Kingdom Hearts. At the beginning of the series, she is 14 years old. During the events of the first game, her heart was separated from her body which led to Sora and Riku both searching for a way to revive her. Kairi's heart was discovered to be in Sora's body, at which point he gives up his heart in order to restore hers, transforming himself into a Heartless. Soon after, Kairi finds Sora's Heartless and restores him back to human form. After Ansem's defeat, Kairi is left behind on the reforming Destiny Islands and separated from Sora at the end of Kingdom Hearts. Sora promises to return to her with Riku, and Kairi waits on the island for their return.

In Kingdom Hearts II, Kairi and all of Sora's friends slowly begin to remember Sora. After Sora's memories had been restored by Naminé, Kairi sends the letter drifting to the sea in hopes of that it will find its way to him. She is later confronted by Axel, who hopes to use Kairi to lure Sora to him. With the help of Pluto, Kairi evades him and heads to Twilight Town, but is captured by Axel soon after. However, Saïx takes Kairi from Axel and imprisons her and Pluto in a jail cell in The World That Never Was. She escapes her cell with the help of Naminé and they are saved from Saïx by Riku, in the guise of Xehanort's Heartless. Riku gives her a Keyblade which she uses to fight off the Heartless that Saïx summons.

Naminé (ナミネ, Namine?) She has the ability to change memories of those in relation to Sora by rearranging them and creating new links between them. Naminé is voiced by Brittany Snow in the English version of Kingdom Hearts II and Iku Nakahara in the Japanese version. Naminé first appeared in Kingdom Hearts: Chain of Memories. Under orders from the Organization, she altered Sora's memories to remember her as a close friend from Destiny Islands, and eventually replacing Kairi. She almost completed her task until Axel allows her to leave his sight. Naminé then manages to reveal herself and the truth to Sora. Once Marluxia is defeated, Naminé has Sora, Donald, and Goofy step into devices that will put them to sleep for a year so she can rearrange the chains of their memories, but break the ones that she created. As a result, Sora's memories of Naminé will be erased. Naminé also helps save Riku in Reverse/Rebirth from Zexion by taking on Kairi's appearance to convince Riku not to refuse the darkness within his heart while drowning in light. When they meet in person, she offers to lock away the darkness of his heart so that it can never hurt him again, but he refuses the offer, opting to battle the darkness. Afterwards she contacted DiZ to help protect Sora, Donald and Goofy.

In Kingdom Hearts II, Naminé is revealed to be a "special Nobody" born from Kairi's heart when it left Sora's body. As Kairi had no darkness in her heart, her heart hid within Sora's body instead of becoming a Heartless when Destiny Islands was consumed by darkness. When Sora impaled himself with the dark Keyblade, his body and soul were used to create not only Roxas, but Naminé as well. As a result of this, she has none of Kairi's memories. Naminé's special birth in conjunction with the fact that Kairi's heart had been in direct contact with Sora's is why, DiZ states, that Naminé's special powers could only affect the memories of Sora and those whose hearts are connected to his, which was why she was used by Organization XIII. Despite DiZ's orders, Naminé visits Roxas in Twilight Town. She appears to him several times, often before he is attacked by Nobodies, acting somewhat as a guide to him. Riku was instructed by DiZ to destroy Naminé since he has no more need of her. However, as seen in Kingdom Hearts II Final Mix, Riku decided to let her go with Axel to repay the favor to her for Castle Oblivion. She is not seen again until near the end of the game where she frees Kairi and Pluto from imprisonment and they attempt to escape from the Organization's stronghold. Naminé gives up her own existence as an independent entity and fuses with Kairi to complete her.

Roxas (ロクサス, Rokusasu?) is the Nobody of Sora. Xemnas found him in Twilight Town and gave him the epithet, "Key of Destiny" (めぐりあう鍵, Meguriau Kagi?, lit. "Happened-upon Key"). In battle, he uses the "Oathkeeper" and "Oblivion" Keyblades, which represent Sora's memories of Kairi and Riku, as well as the power of light. As a stronger Nobody, Roxas controls Samurai Nobodies. Roxas's backstory and his joining of Organization XIII itself will be explored in the upcoming Kingdom Hearts 358/2 Days, for the Nintendo DS. Roxas will be a playable character in the game.

Unlike the other Organization members, Roxas lacks memories of his previous life, due to the short time Sora had spent as a Heartless. During Roxas's time in the Organization, he and Axel became friends, but Roxas leaves to find answers as to why he possesses the Keyblade. He is confronted by Riku, who defeats Roxas and takes him to DiZ. In Kingdom Hearts II, DiZ places Roxas in a virtual Twilight Town, leaving him without any memory of the Organization and with a fabricated identity to throw them off. While here Roxas begins seeing his other self's memories in dreams. Roxas lives an otherwise normal life in "Twilight Town" until Axel infiltrates it to save him. Despite Axel's attempts to stop him and Roxas gaining back his memories of the Organization, Roxas merges with Sora early in the game, which also causes some of Roxas's memories to influence Sora.

Roxas appears twice later on in the game. The first is a battle with Sora, shown only as a cut scene and never fully explained. In Kingdom Hearts II Final Mix, Sora's battle with Roxas is made playable, and a cut scene is added that shows Xemnas explaining that Axel's death triggered the reappearance of Roxas. Roxas appears once again with Naminé before Kairi enters the corridor of darkness back to Destiny Islands. He and Naminé imply that they will live on within Sora and Kairi as both a part of them and as individuals, as seen in the ending cinematic when they smile at each other through Sora and Kairi.