Both "Constant Readers," Stephen King's term of endearment for his loyal fans, and casual moviegoers are excited for the upcoming film "The Dark Tower." The film is based on the sci-fi western horror book series of the same name written by King.

According to Nerdist, it "took 35 years," but writer Stephen King's magnum opus will finally hit the big screen. "The Dark Tower" was initially pitched as "an ambitious TV series adaptation," but right now the only project confirmed is the upcoming movie directed by Nikolaj Arcel. The film will star Idris Elba as the gunslinger Roland Deschain and Matthew McConaughey as Roland's nemesis Walter Padick, the "Man in Black."

"The Dark Tower" is a unique film adaptation because unlike other films based on books, it will instead be a sequel to the book series by King. Before the movie was in production, King revealed that the art for "The Book Tower" books featuring Roland was inspired by Clint Eastwood's classic western characters.

When it was announced that Elba was cast as the gunslinger, some fans didn't take too kindly to the decision. However, King took a stand and tweeted, "To me, the color of the gunslinger doesn't matter. What I care about is how fast he can draw...and that he takes care of the ka-tet." In "The Dark Tower" books, the word "ka-tet" means "a group of people drawn together by ka (destiny) for a purpose" in High Speech, a fictional language.

Tom Taylor will portray Jake Chambers, the first member of Roland's ka-tet, while Katheryn Winnick will play Jake's mother Laurie Chambers. The rest of the ka-tet, Eddie Dean and Susannah, are noticeably absent in the promotional material for "The Dark Tower." Fans can only hope that they show up in the sequel/s.

Another significant change in the upcoming movie is the fact that Roland will start his journey with a crucial item, the "Horn of Eld," that he did not have in the first "Dark Tower" book. King hinted that this means that the gunslinger's journey will be different compared to the one portrayed in the books.

While Roland won't be the main character in a planned "Dark Tower" TV series, it will allegedly be based on the book "Wizard and Glass." It has been reported that Elba may appear occasionally in the show, which will be comprised of 10-13 episodes and is slated for production this 2017.

Abbey Lee will portray Tirana in "The Dark Tower," but her character did not appear until the seventh novel in the series, per Cheat Sheet. Tirana is described as someone "sexy and dangerous" with "fake human skin and cold snake-like eyes."