Organization XIII: Who are they?

(SPOILER)Organization XIII is a series of Nobodies who have joined together to direct the lesser Nobodies into completing their mission of restoring themselves with their Hearts. Unlike the Heartless, they do have a sense of hieraechy, and can coordinate and think independently, in order to acheive a goal. Also unlike Heartless, they do not swarm around the ones they think are the most powerful (even though it does seem that way). Nobodies, if they exert enough of their power, can even influence the Heartless to do their deeds as well, but Nobodies have a general distaste for the Heartless, their cousins of loss.

The Organization itself is comprised of thirteen members, and structures itself based on whenever they joined the Organization. These are most likely the most powerful of all of the Nobodies, for Nobodies believe in strict order. The wisest and therefore, the most powerful, should be in charge, and indeed they are.

I - Xemnas, Xehanort (from Ansem)
The Superior (CoM title), controls Sorcerors, Element of Nothing
II - Xigbar, Braig (Blieg in the American version)
The Freeshooter, controls Snipers, Element of Space
III - Xaldin, Dilan (Dilin in the American version)
The Whirlwind Lancer, controls Dragoons, Element of Wind
IV - Vexen, Even
The Chilly Academic, killed in CoM, Element of Ice
V - Lexaeus, Eleus (Eleaus in the Japanese verion)
The Silent Hero, killed in CoM, Element of Earth
VI - Zexion, Ienzo
The Cloaked Schemer, killed in CoM, unknown Element
VII - Saïx, none
The Luna Diviner, controls Berserkers, Element of Moon
VIII - Axel, none
Dancing Flurry of Flames, controls Assassins, Element of Fire
IX - Demyx, none
The Melodious Nocturne, controls Dancers, Element of Water
X - Luxord, none
The Gambler of Fate, controls Gamblers, Element of Time
XI - Marluxia, none
The Graceful Assassin, killed in CoM, Element of Flower
XII - Larxene, none
The Savage Nymph (kinky!), killed in CoM, Element of Thunder
XIII - Roxas, Sora
The Key of Destiny, controls Samurai, Element of Light