Princesses of Heart

The seven Princesses of Heart are maidens with no darkness in their hearts. If they are all brought together the door to darkness will open. Princesses who lose their hearts do not become Heartless, due to their distinctive lack of darkness.

Members
The seven princesses of heart are:
 * Snow White (from Snow White)
 * Cinderella (from Cinderella)
 * Aurora (from Sleeping Beauty)
 * Belle (from Beauty and the Beast)
 * Alice (from Alice in Wonderland)
 * Jasmine (from Aladdin)
 * Kairi

With the exception of Alice, and the game's new addition Kairi, the Princesses of Heart are also a part of the Disney Princess franchise. Although Ariel appears in the game in her own world, she is not one of the Princesses of Heart, but she is a part of the Disney Princess franchise.

Kingdom Hearts
In order to open the Final Keyhole Maleficent and Riku kidnapped them from their respective worlds. But because Kairi had given her heart to Sora, the keyhole could not be completed. Thus, Xehanort's Heartless used the hearts of the remaining six princesses to create the Dark Keyblade, which could release Kairi's heart from inside Sora. Sora stabbed himself with the keyblade and all the princesses woke up. After Sora sealed Kingdom Hearts the princesses returned to their own worlds.

Chain of Memories
Alice, Jasmine, Belle and Kairi all appeared in Kingdom Hearts: Chain of Memories as figments of Sora memories. Also, by remembering Kairi, Sora could start regaing his lost memories. In Riku's story Naminé appears Kairi to tell Riku not to hide from the darkness in his heart.

Kingdom Hearts II
The seven Princesses didn't have a big role in Kingdom Hearts II. Belle and Jasmine were in thier own worlds. In Tron's world the password to the DTD Dataspace was the princesses names.

Trivia

 * In the Awakening, there are five glass pillars, four of which depict four Princesses of Heart. The fifth is a pink stained glass pillar showing three silhouettes of girls framed by heart shapes. This could have been made to make the player think "Who are these mysterious girls?" Thus, the three silhouettes are more likely a sign that there are three more Princesses remaining who are yet to be captured (Alice, Jasmine and Kairi).