Fortune cajoled this year's top 40 into sharing facts about them you won't find on the Internet (until now).
"That my name is William Adams, not William James Adams or something, that ain't me. But if you Wikipedia me that's what it thinks my name is. And it's wrong. It frustrates me."
NEXT: Aaron Levie
Our 2013 edition of the list features young hotshots who are rocking businesses as diverse as air travel, natural gas, and genetic coding, as well as—if you can believe it— government.