World's 10 richest billionaires
6. Karl Albrecht ($21.5 billion). Albrecht, 89, founded the discount supermarket chain Aldi with his brother Theo. After serving in the German Army during World War II he and his brother took over his mother's small grocery store. He is a very private person and is rarely seen in public since giving up his position in Aldi Süd in 1994. Getty Images
