On the television show "Castle," the character of Richard Castle is a best-selling author who lives a life of luxury with no limits. He enjoys exotic sports cars, wears designer suits and owns both a mansion in the Hamptons and a penthouse in New York City. While this millionaire lifestyle may seem a little over the top, it is well within the reach of many best-selling authors, some of whom have earned hundreds of millions over the course of their careers.

The Top 10 Best-Selling Authors

"Forbes" regularly compiles a list of the world's top authors and details their annual earnings from the most recent year. The top 10 earners as of this writing are:

1. James Patterson, $90 million
2. Dan Brown, $28 million
3. Nora Roberts, $23 million
4. Danielle Steel, $22 million
5. Janet Evanovich, $20 million
6. Jeff Kinney, $17 million
7. Veronica Roth, $17 million
8. John Grisham, $17 million
9. Stephen King, $17 million
10. Suzanne Collins, $16 million

Note that these are annual figures, not total career earnings. Patterson has earned $700 million in a single decade.

How the Top Earners Earn So Much

Authors that consistently earn millions are prolific writers. Danielle Steel has published 128 books over 40 years. James Patterson writes 14 books a year with a variety of co-authors. Most authors on the list have created a series of related novels featuring the same main characters, such as Jeff Kinney's "Diary of a Wimpy Kid" books. Janet Evanovich has completed 20 novels in her Stephanie Plum series. Authors earn not only from the sales of their many books, but also from selling the film and television rights to their stories.

Defining the Best-Selling Author

The term "best-selling author" is difficult to define, as the many best-seller lists have varied methods of calculating sales. Additionally, electronic book sales and print book sales may be given unequal credit. The most influential best-seller list, the "New York Times," gives higher weight to sales of print copies over electronic books. According to "Fast Company," it takes about 20,000 print sales to make the week's "New York Times" best-seller list. The earnings of best-selling authors depend on the deal they (or their agents) negotiated with their publisher and how long the book continues to sell.

Earnings for Best-Selling Authors Who Aren't Superstars

According to the Authors Guild, authors commonly receive 10 percent of sales up to 5,000 copies, 12.5 percent of the next 5,000 and 15 percent after that. Any advance paid to the author before publication is deducted from the incoming royalties from sales. Given the royalties of a standard contract, an author selling 20,000 books priced at $25 would earn $65,625 the first week on the "New York Times" best-seller list. This is not quite the millions superstar authors bank, but if the book continues to sell, these earnings add up to an impressive income.