Satoshi Nakamoto is the founder of Bitcoin and initial creator of the Original Bitcoin client. He has said in a P2P foundation profile.
That he is from Japan. Beyond that, not much else is known about him and his identity. He has been working on the Bitcoin project since 2007.
His involvement in the Bitcoin project had tapered and by late 2010 it has ended. The most recent messages reportedly indicate that Satoshi is "gone for good"
He left some clues about why he is doing this project with the inclusion of the following text in the Genesis block, "The Times 03/Jan/2009 Chancellor on brink of second bailout for banks".