Who has saved the most human lives?

EDIT: ScienceHeroes.com answers this question very well. You can find biographies of the scientists also. The website profiles lifesaving scientists that have saved lives.

Borlaug is in the top 6, but the top is Fritz Haber and Carl Bosch who created "synthetic fertilizer". Karl Landsteiner and Richard Lewisohn are next with the discovery of "blood groups", enabling safe blood transfusions. Edward Jenner, smallpox vaccination, rounds out the top 5.

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Norman Borlaug- Estimated 1 billion

He has saved approximately 1 billion people in his life so far from starvation.

Another top contestant is, believe it or not, Herbert Hoover. Before he ruined his reputation by getting elected president, he earned fame and adulation by arranging for the feeding of millions of people during and after World War I. Estimates of the number of lives saved range from a couple hundred million to 1.4 billion.

But, of course, it's hard to count something that's been prevented from happening.