10. Samuel Robson Walton

• Net Worth: $23.1 B                                                                 
• Source of Wealth: Wal-Mart
• Citizen: United States
• Age: 69

 
It hasn't been all smiles this past year for Wal-Mart heir S. Robson Walton, eldest son of visionary retailer Sam. Wal-Mart boasts sales of nearly $470 billion and employs nearly 2.2 million people in 11,000 stores worldwide. Rob has received about $350 million in dividends in 2013. Before joining Wal-Mart, he was a partner with the law firm of Conner & Winters in Tulsa, Oklahoma. Rob and his siblings have donated about $2 billion to the Walton Family Foundation over the last five years.