HBO continues to add Westeros residents to its “Game of Thrones” prequel pilot, announcing the addition of five more actors.

The new cast members are Marquis Rodriguez, John Simm, Richard McCabe, John Heffernan, Dixie Egerickx, which brings the cast list for the untitled prequel to 16.

No character details are currently available for any of these parts on the prequel pilot, which is currently untitled (unless you are going by Martin’s recent blog post) and set to go into production this summer. However, lead Naomi Watts has been cast as a charismatic socialite hiding a dark secret.

Also Read: 'Game of Thrones' Prequel: Here's Everything We Know About the HBO Pilot So Far

Along with Watts, the cast includes “Harry Potter” alum Miranda Richardson, Josh Whitehouse, Naomi Ackie (who will next appear in J.J. Abrams’ “Star Wars” franchise), Denise Gough (“Guerrilla,” “Angels in America”), Jamie Campbell Bower (“Twilight,” “Mortal Instruments”), Sheila Atim (“Harlots”), Ivanno Jeremiah (“Black Mirror”), Georgie Henley (“The Chronicles of Narnia”), Alex Sharp (“To the Bone”) and Toby Regbo (“Fantastic Beasts: The Crimes of Grindelwald”).

Ordered to pilot last year, the project from Martin and “Kingsman” screenwriter Jane Goldman is set thousands of years before the events of the current “Game of Thrones” series in the era known as the “Age of Heroes.”

According to HBO, the drama “chronicles the world’s descent from the Golden Age of Heroes into its darkest hour. And only one thing is for sure: from the horrifying secrets of Westeros’ history to the true origin of the white walkers, the mysteries of the East to the Starks of legend … it’s not the story we think we know.”

Goldman wrote the pilot from a story she developed alongside Martin. She will serve as showrunner and will executive produce alongside Martin, James Farrell, Jim Danger Gray, Vince Gerardis, Sara Lee Hess, and Daniel Zelman. SJ Clarkson will direct the pilot and also executive produce. Chris Symes is co-executive producer.

HBO kicks off the final season of “Game of Thrones” on April 14.