J.K. Rowling

Author J.K. Rowling was a single mother living on welfare when the first Harry Potter novel debuted in 1997.

The series has sold more than 600 million copies worldwide to-date, the primary source of Rowling's billion-dollar fortune.

The eight Harry Potter film adaptations grossed almost $7.7 billion at the global box office, at the time the highest-grossing franchise in movie history.

She previously dropped off the billionaires list in 2012 due to her substantial philanthropy. She has donated more than $200 million to charity over the past 20 years.

In the years since, the Harry Potter brand has only expanded, into theme parks, video games, art exhibitions and a stage play, all of which have set sales records.

When the first Wizarding World attraction opened in 2010, Universal's Orlando theme park saw a 36% jump in attendance. Universal has since added it to five other parks around the world.