Who might he, she or THEY be? The world may never know, but this address just crossed the $1billion dollar mark in bitcoin:
It looks like they were pretty wealthy to begin with, because some of his earliest trades were in the millions, but if they weren't billionaires before they sure are now.
This is the Bitcoin rich list:
https://bitinfocharts.com/top-100-richest-bitcoin-addresses.html
Hope they do something useful with it!