You might think enormous wealth guarantees instant notoriety.
It doesn't. Some of the world's richest people manage to stay below the detection of the public despite being worth billions. We're not talking about being famous and reclusive. We're talking about being flat-out unknown among the masses.
Sure, most people know of billionaires like corporate financier Carl Icahn, Hong Kong business magnate Li Ka-shing and Italian media mogul and former Prime Minister Silvio Berlusconi.
But what of Susanne Klatten? Or Birgit Rausing? Or John Sall? They've got the kind of money the rest of us can only dream of. And yet here's betting that you've never heard of them, even if you're familiar with the companies or products that made them wealthy.
Sall, worth $4.4 billion when Forbes last valued his fortune in September 2007 as part of our annual Forbes 400 rankings, co-founded privately held software giant SAS, where he remains executive vice president.
Klatten is a member of Germany's Quandt family, which owns a controlling stake in automaker BMW. She also owns 50% of German chemical company Altana. Forbes last estimated her fortune in March at $9.6 billion as part of our annual billionaire rankings--although that was before she received half of the proceeds from Altana's $6 billion sale of its pharmaceutical business to Nycomed last year.
And Rausing? She and her three children have a combined fortune of about $11 billion after inheriting ownership of packaging giant Tetra Laval. Never heard of Tetra? Ever slurp down a refreshment from a juice box? That's them.
Sifting through the names of obscure billionaires can invite some surprises. For example, take the case of Peter Buck. No, not the guitarist from R.E.M.--this Peter Buck lent a family friend $1,000 in 1965 to start a sandwich shop. Today, the result is Subway Restaurants.
You'd think that being co-founder of a fast-food giant would gain you some name recognition. But it's probably safe to say that few people not named Jared have ever heard of Buck.
Much the same could be said about Bradley Hughes. No, not the PGA golfer from Australia. Like Buck, Hughes started a business that you've probably heard of. It has 2,100 locations in 38 states. If you're an incurable pack rat, you might be a customer.
Give up? Hughes is the founder and chairman of Public Storage.
Then there's copper-mining magnate Vladimir Kim, who cuts an unlikely figure on a lot of different levels.
The guy's worth a cool $5.5 billion, making him the richest person in the post-Soviet republics outside of Russia. He's also a lot wealthier than Silicon Valley billionaires Meg Whitman, Jerry Yang and John Doerr, despite the presumed geographic disadvantage of hailing from Kazakhstan.
And Kim is the richest ethnic Korean on the planet, with a fortune that far surpasses even that of Samsung Group Chairman Lee Kun-Hee.
Despite managing to stay virtually unnoticed by the rest of the world, even press-shy billionaires will occasionally surface in the public eye. Sometimes it's by choice. Sall, a fan of Barack Obama, co-hosted a fund-raising event in Chapel Hill, N.C., last year for the Illinois senator and Democratic presidential hopeful.