"Fifty Shades" of pandemonium is circulating around the erotic trilogy that has everyone talking and revamping their sex lives, and now it has surpassed "Harry Potter."

The steamy "Fifty Shades" trilogy, written by bestselling author E.L. James, tells the story of 22-year-old recent college grad Anastasia Steele, who enters into a dominant/submissive sexual relationship with 27-year old sexy billionaire Christian Grey, through an "agreement," and both explore the world of BDSM (bondage, dominance, submission, masochism).

"Fifty Shades of Grey," along with the other two novels, "Fifty Shades Darker" and "Fifty Shades Freed," sold more than four million copies in print and on Kindle since they went on sale in March, making James the best-selling author of all time at the U.K. website of Amazon.

The first novel is outselling JK Rowling's final installment, "Harry Potter and The Deathly Hallows," by more than two to one, according to The Sun.

Gordon Willoughby, EU director of Kindle, said, "If JK Rowling was the literary phenomenon of the last decade, then EL James looks certain to take that mantle in the current decade."

"In just four months, EL James has become Amazon.co.uk's biggest-selling author of all time, which is truly remarkable when you consider that we've been selling books for almost 14 years."

With "Fifty Shades of Grey" flying off the shelves, there is no doubt that fans will stand in line to wait for this erotic romance film.

Movie rights to the trilogy were bought up by Universal and Focus Features, U.S. media reported in March.

Recently, Michael De Luca and Dana Brunett, producers of the Oscar-nominated film "The Social Network," have been picked as the production team for the erotic "Fifty Shades of Grey" film adaption.

Fans are already picking their favorite stars for the casting of Anastasia and Christian.

"Game of Thrones" star Emilia Clarke, "Gilmore Girls" star Alexis Bledel, "Percy Jackson & the Olympians" star Alexandra Daddario, "The Vampire Diaries" star Ian Somerhalder, "DietTribe" Jessie Pavelka, "True Blood" Alexander Skarsgard, and "White Collar" star Matt Bomer are just some of the popular actors/actresses that have been linked to the two steamy roles.

Click HERE to see who the front-runners are this week for the two crucial roles of Anastasia Steele and Christian Grey.