Fortune's annual list is filled with executives who defied expectations (buying a newspaper, leaving luxury for Apple), executed big turnarounds, and delivered stellar results for their shareholders.
Executive chairman, Twitter; CEO, Square
--40 Under 40 --Returnee
Dorsey continues to wear two hats, running mobile-payments platform Square while chairing newly public Twitter.
NEXT: Ajay Banga
What the two have in common is a rare form of design thinking powered by unfettered conviction.