Net Worth: $26.5 billion UP
Widow of John Walton inherited her wealth after the former Green Beret and Vietnam War medic died in an airplane accident near his home in Wyoming in 2005. Now world’s richest woman, she got an extra bump in her fortune because of her late husband's early investment in First Solar; shares up nearly 500 percent since 2006 initial public offering. But bulk still comes from her holdings in Wal-Mart, the retailer founded by her father-in-law Sam Walton and his brother James in 1962. Today Wal-Mart has sales of $405 billion, and employs more than 2.1 million people. The philanthropist supports museums, education and organic gardening.
(L. Matthew Bowler) More from Forbes: The World’s Richest Women Billionaires 2011 The World’s Youngest Billionaires 2011 Notable Newcomer Billionaires 2011