Ben Bernanke

The Zen-like chairman of the U.S. Federal Reserve might not have topped the list solely for turning his superb academic career into a blueprint for action, for single-handedly reinventing the role of a central bank, or for preventing the collapse of the U.S. economy.

But to have done all of these within the span of a few months is certainly one of the greatest intellectual feats of recent years. Not long ago a Princeton University professor writing paper after paper on the Great Depression, "Helicopter Ben" spent 2009 dropping hundreds of billions in bailouts seemingly from the skies, vigilantly tracking interest rates, and coordinating with counterparts across the globe.

His key insight? The need for massive, damn-the-torpedoes intervention in financial markets. Winning over critics who have since praised his "radical" moves (including Nouriel Roubini, No. 4 on this list), he now faces an uphill battle in his bid for permanently expanded Fed powers. The radicalism is far from over.

"Those who doubt that there is much connection between the economy of the 1930s and the supercharged, information-age economy of the twenty-first century are invited to look at the current economic headlines -- about high unemployment, failing banks, volatile financial markets, currency crises, and even deflation. The issues raised by the Depression, and its lessons, are still relevant today." --Bernanke,