=14. Dan Brown — £7.1 million ($9.5 million)
Dan Brown is best-known as the author of the mystery thriller "The Da Vinci Code," which was turned into a film in 2006, three years after its publication. He is set to publish an abridged version of the novel for young adults on September 8 with Penguin Random House.
=14. Rick Riordan — £7.1 million ($9.5 million)
Rick Riordan made his millions from writing the "Percy Jackson and the Olympians" series. The five-book series, which is about a 12-year-old who discovers he is a son of Poseidon, has since been turned into graphic novels and films.
=14. George R.R. Martin — £7.1 million ($9.5 million)
George R.R. Martin has spent five years writing "The Winds of Winter," the sixth part to his fantasy epic, "A Song of Ice and Fire." It was turned into the HBO television series "Game of Thrones" in 2011, making Martin one of the world's most famous authors.
=11. Paula Hawkins — £7.5 million ($10 million)
British author Paula Hawkins is best known for her 2015 novel, "The Girl on the Train." So far, Hawkins has sold 11 million copies of her novel worldwide, with a film adaptation due for release in October 2016.
=11. John Green — £7.5 million ($10 million)
John Green is famous for writing several novels, including "Looking for Alaska," "An Abundance of Katherines," "Paper Towns," and "The Fault in Our Stars," which sold over 10 million copies following its release and became the best-selling book of 2014.
=11. Veronica Roth — £7.5 million ($10 million)
American novelist and short story writer Veronica Roth became a household name when her book "Divergent" became a New York Times bestseller in April 2011. She has also published two sequels, "Insurgent," and "Allegiant." All three have been adapted for film.
8. EL James — £10.5 million ($14 million)
E.L. James' "Fifty Shades" series of erotic novels started out life as a fan fiction tribute to the "Twilight" novels by Stephenie Meyer. James released "Grey" — a spin-off of her bestselling books, in June 2016.
=7. Nora Roberts — £11.3 million ($15 million)
Nora Roberts has written more than 215 novels, but is best-known for her romantic fiction. Her most recently published works include "Bay of Sighs," published in June 2016, and "The Obsession," which was published in April during the same year.
=7. Danielle Steel — £11.3 million ($15 million)
Danielle Steel has sold 650 million copies of her romance novels throughout her career. Her most recent book, "Magic: A Novel," was released in July 2016.
=7. Stephen King — £11.3 million ($15 million)
Stephen King is one of the world's wealthiest authors, having amassed an estimated £338 million ($450 million) throughout his sci-fi and horror novel-writing career. His most famous works include "The Shining," "It," and "Misery," which have all been turned into films. His memoir, "On Writing," gives valuable insights on how to become an author yourself.
4. John Grisham — £13.5 million ($18 million)
Lawyer turned crime novelist John Grisham has sold more than 300 million copies of his books worldwide and inspired several blockbuster movies like "The Firm" and "The Pelican Brief." According to the Guardian, he plans to give away his latest work , "The Tumor," for free.
3. JK Rowling — £14.3 million ($19 million)
J.K. Rowling is one of the world's best-selling authors, but she wasn't always so successful. "Harry Potter and the Philosopher's Stone," the first book in the "Harry Potter" series that made her famous, was rejected by several publishers before being picked up by Bloomsbury in 1997.