The highly-anticipated TV adaptation of Terry Pratchett and Neil Gaiman's 1990 novel "Good Omens," has cast members David Tennant and Michael Sheen dying their hairs red and blonde to be more suited for their roles.

Tennant ("Doctor Who") will be playing the role of the demon, Crowley, alongside Michael Sheen as his angel friend, Aziraphale.

Following this casting news, Michael McKean ("Better Call Saul") confirmed via Twitter his portrayal of the novel's The Witchfinder Army sergeant, Shadwell. Jack Whitehall, on the other hand, will be playing the role of Newton Pulsifier.

Book co-author Gaiman also announced via Twitter that Adria Arjona will bring prophet Anathema Device to life, together with Ned Dennehy and Ariyon Bakare as the soon-to-be TV versions of Hastur and Ligur, and Nina Sosanya as Sister Mary Loquacious.

The young actor for the role of Adam, as well as his horsemen War, Famine, Pollution, Pestilence and Death, will be revealed by Gaiman.

"I first read 'Good Omens' as a teenager and it's been one of my favorite stories ever since," Sheen told Variety. "Good Omens," which the six-part Amazon-exclusive TV series is based on, is comical take of the classic horror movie "The Omen," but in this story, the Antichrist is raised as Adam, a charming boy with English upbringing. Adam gets sucked into this end-of-the-world event where he becomes friends with an angel, a demon, a prophet, the horsemen of Apocalypse and many other characters.

Tennant played "Jessica Jones" season 1 villain, Killgrave, in the Marvel TV series from Netflix. He is also known as Barty Crouch Jr. from "Harry Potter and the Goblet of Fire."

When Pratchett passed away in 2015, Gaiman told the fans of the novel that the long-requested TV series was not going to happen. In a memorial for his friend back in 2016, Gaiman received a posthumous letter from Pratchett that served as a thumbs-up from heaven to get the filming for the TV series finally started.