When we talk about billionaires of Greek origin, we often think of the legendary Aristotelis Onassis, the shipping magnate whose life was picture-perfect, including a relationship with singer Maria Callas and a marriage to JFK's widow. But despite his fame, everything seems to indicate that Onassis wasn't the richest magnate of his time, a place that belonged to Stavros Niarchos, curiously his brother-in-law. We'll learn the reason for this family connection later.