Satoshi Nakamoto
The creator of Bitcoin, Satoshi Nakamoto, is the worlds most elusive billionaire (worth more than $7B as of November 2017). Very few people outside of the Department of Homeland Security know Satoshis real name. In fact, DHS will not publicly confirm that even THEY know the billionaires identity. Satoshi has taken great care to keep his identity secret employing the latest encryption and obfuscation methods in his communications. Despite these efforts (according to my source at the DHS) Satoshi Nakamoto gave investigators the only tool they needed to find him his own words.