The Nobodies

Beware of the Nobodies, the wanderers and the lost souls. The beings without hearts searching for somewhere to belong.
Organization XIII (XIII機関, Jūsan Kikan?) is a fictional group of characters featured in Square Enix and Disney Interactive Studios' Kingdom Hearts video game series. Kingdom Hearts is a crossover of various Disney settings based in a universe made specifically for the series. The group is comprised of thirteen Nobodies, or beings without hearts.
Source: Wikipedia