Glowing Eyed Unknown

An unknown who is immediately recognized by several traits. He was first seen in Deep Dive. He seems to have the ability to walk through walls, like a ghost like creature. The fact that this unknown has the ability to do this, leads some to believe that he is not a shell but the heart of a character.

With the glowing eye and heartless symbol that appears before he walks through the rock, this unknown appears to be the most sinister of the bunch. He could be a heartless himself.

Another distinctive trait of this unknown is his boots which are clearly seen in the above shot. Long boots that are pointed with the pants leg tucked in. Compare these pair of shoes with the one that the dual wielding unknown was wearing during deep dive.

The clear difference here is the shoe buckle and rounded front and his pants our not tucked in (from other shots). Obviously, we can tell that the dual wielding unknown and this own are not one and the same

One last point about this unknown, it was said to him that "He looks just like you". It is assumed that this is a reference to Sora based on the extra scene from final mix and so we can assume that this unknown is either Sora or someone who looks like Sora. That is of course assuming that this is a reference to Sora.