5. Frank Lowy

•  Net Worth: $5.3 B                                                                      
•  Source of Wealth: shopping malls
•  Citizen: Australia
•  Age: 83

Frank Lowy is founder of one of the world's biggest listed retail property groups, Westfield, which owns 104 shopping malls in Australia, New Zealand, the U.K., the U.S. and Brazil. He enjoyed a $1 billion jump in wealth as his Westfield Stratford City--opened in September 2011 near the London Olympics site--proved a huge success.