Bit ironic, isn't it? Christopher Lee played Count Dooku in the Star Wars prequels.
What could that be? Maybe whoever this fella is, he's like Vanitas, Xemnas, and Ansem SOD - he controls a new faction. And that symbol is that faction's emblem. This could be the foreshadowing of a new race of enemies in future games... just as with Enigmatic Xemnas in KH1 Final Mix... Just an idea.
Another minor note - I don't like how they just reused the Unknown model. Just like Vanitas, Ven, and Vanitas Sentiment. I wish for this boss they'd use a new model, like Lingering Sentiment. Aw well, budget and what not. Aw well.