Heartless:
Heartless are the darkness in hearts of living beings given shape and form. They have a thirst for hearts, and are most attracted to pure hearts, such as Sora's. Their existence became known after one was created by Ansem, as revealed by his reports. Emblem Heartless were later created by Xehanort.
Though the origin of the Heartless is not explicitly described or shown, there was one point where there was not a single person with darkness in their heart, and only light existed, and as such all the worlds were connected. However, people began to grow selfish over the light, and thus darkness was born in their hearts. This darkness eventually consumed the light, but the children of light were able to craft new worlds, though they would remain separate. However, the greatest light would reside in the darkness, and until the day comes when that light breaks through the darkness, darkness would continue to thrive.
Heartless Emblem:
Nobodies:
A Nobody is what is left behind by those whose hearts have been consumed by Heartless. They are made of body and soul.
Nobodies are born when a heart is swallowed by darkness and becomes a Heartless. They are the remaining parts left behind by the heart: the body, giving a Nobody form, and the soul, giving the Nobody life. However, only those with strong wills such as Sora are actually able to continue on as Nobodies. Those with the strongest wills manage to retain human forms with some slight changes to their appearance, while the rest possess malformed, barely humanoid appearances. Therefore, the more humanoid a Nobody, the more powerful it is. This is opposite the nature of the Heartless, whose form is more monstrous the stronger the original heart is.
Because of their missing hearts, Nobodies lack emotion. Although, some humanoid Nobodies pretend to possess emotions, fooling others as well as themselves. On the other hand, Nobodies manage to keep their memories of their former lives, but unusual Nobodies lack memories of their former selves. Such memories are the reason why they can pretend to have emotions. However, even though Nobodies don't have emotions, they can think and plan (as opposed to the Heartless, which are mindless and simply act on instinct, with a few exceptions), and possess memories of their past lives despite their lack of hearts. Nobodies also seem to be able to experience physical sensations, such as pain, as they negatively react to taking damage
Nobody Emblem:
Keyblades:
The Keyblades are mysterious weapons that are heavily featured in the Kingdom Hearts series. The Keyblade is a main part of the battle between Darkness and Light.
The origins of the Keyblades is, thus far, unclear. Each game references the special qualities of the wielders and some give vague explanations of the Keyblades' power, but none have shown where the Keyblades originated, how they are created, or what their original purpose might have been. One legend mentioned in Kingdom Hearts states that the Keyblade master saved the world, while another said he wrought chaos and destruction upon it. While these legends may appear to contradict themselves, it can be assumed that the Keyblade master chooses how to use the Keyblade, whether for good or evil. The Keyblade is known throughout the worlds as a unique and powerful weapon.
This next part is about a new enemy in the upcoming game Birth by Sleep. It refers to the Unbirths. I will provide some pictures so you can have a visual.
The Unbirth possess some sort of connection to the Heartless and the Nobodies of the main series.
They are, in essence, "the opposite of human life."
Several types of Unbirth have been shown in scans, including a small, skinny creature, blue in color, and a large creature also colored blue. They all seem to feature odd red eyes and large, zig-zagging antennae/ears. There are flower-like Unbirths that look like potted flowers with vines for arms that seems to spin like a top and pot-like Unbirths that are simply red pots with bat wings. Also, there are raven-like Unbirths and Unbirths that are reminiscent to boots. A rabbit-like Unbirth is also shown, with long floppy ears and tiny, stubby legs.
Unbirth Emblem:
Look at the other Topic for the Unbirth pictures.
All info from:
Kingdom Hearts Wiki
