Inhabitant: The people. The human-beings or close-to-human/humanoid physical living beings that exist on each and every world. They vary in their general appearance and, to some extent, their physical abilities.
The selected few are those of pure hearts, be that hearts filled with pure light or those filled with pure darkness. They wield the most powerful weapons, the Keyblades.
Mysterious weapons that come into the hands of the worthy. Keybladers may be the hope to turn the tide of darkness away, their own keyblades resonates with their nature ... mimicking them and gaining abilities most suited to their users.
Intelligent Heartless: Like 'Ansem' from the first 'Kingdom Hearts' Game. They are heartless who have been able to regain consciousness and know who they are. This allows themselves full control over their own bodies and actions and, with the power of darkness, they give rise to some of the most powerful dark beings to exist.
Intelligent Heartless succumb to light fairly quickly, but that opens the way to enlightenment and they soon may feed off it and soon crave for power. They are deadly, capable of summoning armies of heartless with just mere thoughts.
Intelligent heartless can even create their own personal servants like 'Ansem', that may fight for them. But being a heartless, their natural bloodlust may get in the way of their sanity.
Empowered Nobody: Deadly 'non-exsistant beings'. Superior to normal 'nobodies', these rare individuals were like those of the former Organization XIII ... but with a twist. When their human form died, it gave rise to both a nobody and an intelligent heartless. An empowered nobody ... results when the nobody consumed it's other half, the Intelligent.
With their ability to control darkness and summon the armies of 'Nothing', the nobodies, the Empowered nobodies turn out to be one of the sinister groups. Their plans unknown, and even their shifty group which models itself after the organization ... who knows what they are after?
They are proficient at combat, provided that their human form and Intelligent had such skills. Though their human appearance may vary ... they still remain partially ... human. For they have consumed their heartless, thus in a sense tried to bring back their lost heart. But no, instead the Empowered is bestowed with the powers of "Nothingness" and the powers of "Darkness".
They have no hearts, but since they once did ... manipulating people turns to be a simple task