Net worth: $1 billion
Joanne “J.K.” Rowling was a single, working mom living on welfare in Edinburgh, Scotland when she wrote the first Harry Potter book (most of it in a cafe while her daughter was sleeping). The best-selling books have gone on to be one of the highest-grossing film franchises ever. For many years, Rowling, 46, was a billionaire, but has since given nearly $160 million of her money away to charities. Harry Potter would approve!