Apple

Steve Jobs, 54, Chief Executive Officer in 1976-85 and again since 1997

Biggest accomplishment in this job: Perhaps the greatest entrepreneur of the past 50 years, Jobs sparked the PC revolution with the Apple I and II, and then redefined the product with the Mac in 1984. When Apple (AAPL) seemed doomed, he staged a comeback, developing the iMac, the iPod and maybe most remarkably, the iPhone. He's again working part-time after a medical leave of absence for a liver transplant.

Previous experience: Before founding Apple at age 21 with Steve Wozniak, he dropped out of Reed College and held short-lived jobs with Hewlett-Packard (HPQ) and Atari.

Innovation philosophy: Jobs marries an understanding of consumers with a focused perfectionism on all aspects of design. While Apple rarely invents underlying technologies, it's a master at spotting their potential and combining them in new ways to create new form factors and categories.