Otto Boehringer

Otto Boehringer derives his fortune from Germany's Boehringer Ingelheim, the world's largest privately-owned pharmaceutical company.

Now in its fifth generation, Boehringer Ingelheim was founded in 1885 but traces its entrepreneurial roots back to 1817.

The company grew by selling ingredients to pharmacies, textile merchants and the food industry and had a workforce of 1,500 by 1939.

Today it employs 53,000 and boasts a presence in 130 markets.

Otto along with 14 members of the family own equal parts of the company.