Nikolaj Coster-Waldau is among a new wave of cast additions for HBO's epic fantasy pilot "Game of Thrones."

After previously staring in "New Amsterdam" and recently in Ronald D. Moore's Fox pilot "Virtuality," Coster-Waldau steps into a key role as notorious warrior Jaime Lannister.

Also joining the cast: Tamzin Merchant (Showtime's "The Tudors"), who'll play Daenerys Targaryen, an exiled dragon princess; Richard Madden ("Hope Springs") as Stark's eldest son, Robb; Iain Glen ("Into the Storm") as Ser Jorah Mormont, a knight seeking redemption; Alfie Allen ("The Other Boleyn Girl") as Theon, Stark's young ward; Sophie Turner, as Stark's eldest daughter, Sansa; and Maisie Williams as Stark's resilient daughter, Arya.

More announcements for "Game of Thrones'" large ensemble cast are expected soon as the series grows into one of the most buzzed-about titles on HBO's development slate.

Based on author George R.R. Martin's bestselling "A Song Of Ice And Fire" novels, the series follows the tragic and brutal struggle between royal families to secure ultimate power of the vast lands of Westeros, which face threats from exiled royalty, a winter that could span years, and mysterious forces from beyond a mammoth ice wall. Behind these events, dangerous men and women embrace a dangerous game of treachery, stopping at nothing to win the throne.

After its 1996 debut, "A Game Of Thrones" won the Locus Award for Best Fantasy Novel and captured nominations for the Nebula and World Fantasy awards. More awards followed for subsequent books in the series. Seven novels are planned, with the fourth volume, "A Feast For Crows," being the latest.

"Yes, I'm thrilled with this cast," Martin said in a LiveJournal post Thursday. "David [Benioff] and Dan [Weiss] and Tom [McCarthy] and casting director Nina Gold are assembling a terrific group of actors."

Benioff ("Troy," "The Kite Runner") and Weiss penned the script and serve as executive producers. Martin, Guymon Casady, Carolyn Strauss and Vincent Gerardis also hold executive producing duties.

Previous additions to "Game of Thrones" include Peter Dinklage as Tyrion Lannister, Sean Bean (Lord of the Rings) as Ned Stark, Jennifer Ehle as Ned's wife Catelyn, Mark Addy ("Still Standing," "The Order") as king Robert Baratheon, Kit Harrington as Starks illegitimate son Jon Snow, Harry Lloyd as the exiled prince Viserys Targaryen, and Jack Gleeson as King Robert's unruly son Joffrey.

McCarthy, who worked with Dinklage on "Station Agent," will direct.

"Game of Thrones" begins filming in Belfast, Northern Ireland in late October. If HBO picks up the pilot, it will span a novels worth of material per season.