7. Alexandra Andresen

Norwegian heiress Alexandra Andresen is the daughter of Johan H. Andresen Jr, a Norwegian industrialist and the owner of Ferd AS. She then inherited 42% of the company from her father. As of 2016, Alexandra Andresen is known to be the world’s youngest billionaire with an estimated net worth of $1.2 billion.

She shares the title with her sister Katharina, who also inherited another 42% of the company and is worth the same. Alexandra and Katharina are 21 and 20 years old respectively.