6. John Chambers
Chairman and CEO
The mark of any great perennial leader is to know when it's time to go back to the business that made you great in the first place. That's what Chambers did this year by slimming down Cisco and refocusing the giant on its networking roots. The result is a stronger and more sales-and-channel-savvy Cisco. That sound you hear is the thundering Cisco herd coming on strong in 2012.