Maxina

Maxina is the result of a failed experiment intended to force a Nobody to become a Somebody. Unlike with Sora and Roxas, this experiment involved bonding a strong Emblem Heartless to the humanoid Nobody that was Maxina, in an attempt to allow the Nobody persona to remain dominant even when complete. However, the Organization did not forsee the disorder that an unmatching heart and body would create. Most Nobodies have a body and mind - Maxina doesn't even have that much.

The Heartless' incompatible heart did allow Maxina to regain his emotions, but unfortunately these work against his thoughts, and so his mind is constantly derailed. Utterly deranged, he no longer needs any form of contact, and so is left alone until he is released as a weapon against the Organization's enemies. The free-form chaos of battle is the only thing Maxina can still cope with, and in fact he excels at it - not only are his actions completely unpredictable to the enemy, but he is not even hindered by any emotional reluctance to fight.