Answer: J.K. Rowling

To say the Harry Potter book series and ensuing movie, toy, and general marketing franchise took the world by storm would be an understatement of enormous proportions.

The novels, seven in all released between 1997 and 2007, have sold over 400 million copies across 67 languages. That alone would have brought great wealth to their author, J.K. Rowling, but the ensuing related merchandise and film franchise pushed the value of the Harry Potter brand to over $15 billion.

More than a little bit of that wealth found its way back to J. K. Rowling who, in the process, became the world’s first person to become a billionaire by way of their fiction writing career. Her stint as a billionaire didn’t last for long though; between the high tax rate in the UK and Rowling’s donation of so much money to charity, she quickly lost her status as a billionaire.