6. Clelia Haji-Ioannou (Net worth: $1.42 Billion)
Clelia Haji-Ioannou is a billionaire, thanks to her stake in discount airline EasyJet founded by her brother Stelios. Clelia owns over $40 million in real estate, mostly in Monaco, Cyprus, Athens and London. She also claims to have a multi-million dollar art collection of pieces she has bought over the past 20 years.