Robert Smith: $2.5 billion
Image; Hope Dworaczyk and Robert Smith.Oprah Winfrey: $3 billion
Oprah Winfrey, 63, is the only African-American woman to make the Forbes billionaire list. She overcame a tough childhood to become the well-known and beloved media mogul she is today. While generous with her wealth, Winfrey still maintains an enviable lifestyle. Earlier this year, Winfrey delivered the commencement address at Smith College, telling graduates the secret to success is serving others.
Isabel Dos Santos: $3.1 billion
Isabel Dos Santos and Sindika Dokolo.
The wealthiest of the three woman to make this list, and the youngest black billionaire in the world, 44-year-old Isabel Dos Santos is the daughter of Jose Eduardo dos Santos, who has been president of Angola since 1979. Her fortune comes from multiple investments, many of which are controversial and linked to her father, according to Forbes, although Dos Santos maintains her investments are private and independent.
Mike Adenuga: $6.1 billion
Nigerian Mike Adenuga, 64, is chairman of telecommunications company Globacom, which has 36 million subscribers, as well as the majority owner of Lagos-based oil company Conoil, according to Bloomberg. While earning an MBA from Pace University in New York, he drove a taxi to pay the bills. Today, Adenuga, who has seven children, is the second-wealthiest man in Nigeria, according to Forbes.