Net worth: $50.2 billion
Wealth source: Berkshire Hathaway
Residence: Omaha, Neb.
World Rank: 4th
Mr. Buffett is widely considered the best investor of the past century. His investment firm Berkshire Hathaway operates a broad range of businesses, including Geico insurance and MidAmerican Energy. It also owns over $1 billion in Coca-Cola stock, as well as shares of Procter & Gamble and American Express.
Buffett has pledged to give away nearly all of his wealth to charitable causes, and is lately famous for being an outspoken advocate of higher tax rates for wealthy Americans.