02/14/2009 05:12 am ET Updated May 25, 2011

Unknown Billionaires: Forbes' Richest People You've Never Heard Of

When you think of the richest people in the world, the name Riley Bechtel probably doesn't come to mind.

It should. Bechtel is a member of the exclusive billionaires club. We valued his net worth at $5.5 billion when we calculated our Forbes 400 list in late August--that's above Yankees owner George Steinbrenner III, television hostess Oprah Winfrey and Hollywood king Steven Spielberg.

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