Warren Buffett

Iconic investor crowned the world's richest man in march as Berkshire Hathaway shares ran up 25% between July 2007 and February 2008. Berkshire stock has fallen 15% since, erasing $12 billion from Oracle of Omaha's fortune in 6 months and forcing him to cede the title back to friend and bridge partner Bill Gates. Son of Nebraska politician delivered newspapers as a boy. Filed first tax return at age 13, claiming $35 deduction for bicycle. Studied under value investing guru Benjamin Graham at Columbia. Took over textile firm Berkshire Hathaway 1965. Today holding company invested in insurance (Geico, General Re), jewelry (Borsheim's), utilities (MidAmerican Energy), food (Dairy Queen, See's Candies). Also has noncontrolling stakes in Anheuser-Busch, Coca-Cola, Wells Fargo. Berkshire Hathaway sales in 2007: $118 billion. Issued a challenge to members of The Forbes 400 last October; said he would donate $1 million to charity if the collective group would admit they pay less taxes, as a percentage of income, than their secretaries. Irrevocably earmarked the majority of his Berkshire shares for charity in 2006, mostly to the Bill & Melinda Gates Foundation. Has given $6 billion worth of shares so far.