A Spanish purveyor of cut-price women's high fashion was the surprise inclusion in the top three of Forbes magazine's annual rich list.
Amancio Ortega, whose Inditex fashion group includes the popular Zara chain, rose from seventh to third on the annual billionaires list after almost doubling his wealth from last year - up from $US31 billion in 2012 to $US57 billion.
Mexican mobile phone tycoon Carlos Slim again topped the list with a fortune of $US73 billion, ahead of Microsoft chairman Bill Gates on $US67 billion. Mr Ortega pushed Warren Buffett, the US investor, into fourth on the list.
Mining magnate Gina Rinehart was confirmed as the richest Australian - and the world's 36th most wealthy person, with a personal fortune of $US17 billion - ahead of media mogul Rupert Murdoch (91st, $US11.2 billion), miner Ivan Glasenberg (175th, $US6.7 billion) and casino owner James Packer (198th, $US6 billion).
Mr Slim, who controls America Movil, led the listing for the fourth consecutive year, with his $US73 billion an increase of $US4 billion from the previous year. Gates added $US8 billion.
Asia's richest man, Li Ka-shing, came in eighth with $US31 billion. He owes his fortune to his sprawling transportation, trading and energy businesses.
The richest woman on the list is Liliane Bettencourt, whose L'Oreal-based fortune was estimated at $US30 billion (9th).
The media-shy Mr Ortega left school when he was 12 to work as a shirtmaker's delivery boy, to help support his poor family. He learnt fast and began making gowns and lingerie in his living room along with his first wife, Rosalia Mera.
He realised customers wanted affordable versions of catwalk trends and opened his first Zara shop in the Spanish city of La Coruna in 1975.
Experts credit Zara with transforming the business through "fast fashion". Affordable imitations of catwalk designs can move from drawing-board to stores within two weeks.
One of the Forbes list's biggest losers is Facebook's Mark Zuckerberg (66th), whose fortune dropped by $US4.2 billion due to the decline in his company's stock value. But the year's biggest loser was Brazilian oil and mining tycoon Eike Batista (100th), whose fortune dropped by $US19.4 billion - or about $US50 million a day.
The 1426 people who made the list include 200 new billionaires. Their total net worth is $US5.4 trillion, up 17 per cent from last year, with an average net worth of $US3.8 billion.
The US leads the list with 442 billionaires, followed by Asia-Pacific (386), Europe (366), the Americas (129) and the Middle East and Africa (103).
The amount Facebook founder Mark Zuckerberg's fortune fell by last year
Amount the fortune of Eike Batista fell each day last year
The top 5 billionaires
Carlos Slim $US73 billion
Bill Gates $US67 billion
Amancio Ortega $US57 billion
Warren Buffett $US53.5 billion
Larry Ellison $US43 billion
The top 5 Australians
Gina Rinehart $US17 billion
Rupert Murdoch $US11.2 billion
Ivan Glasenberg $US6.7 billion
James Packer $US6 billion
Andrew "Twiggy" Forrest $US5.7 billion