Author of the hugely successful Harry Potter series, Joanne Kathleen Rowling, has a net worth of £560 million – making her the world's richest author. Rowling wrote the first Potter books on a manual typewriter while a single mother living on benefits. The manuscript for the first Harry Potter novel was rejected by 12 publishers and when finally accepted, Rowling received an advance of just £1,500. Harry Potter is the highest-grossing film series of all-time and the brand has been estimated to be worth as much as £10 billion.