HBO’s House of the Dragon has rounded out its main cast with the addition of Rhys Ifans, Steve Toussaint, Eve Best and Sonoya Mizuno.

They join Paddy Considine, Olivia Cooke, Matt Smith and Emma D’Arcy in the straight-to-series Game of Thrones prequel from George R.R. Martin, Ryan Condal and Miguel Sapochnik.

Based on Martin’s Fire & Blood, the series, which is set 300 years before the events of Game of Thrones, tells the story of House Targaryen. I hear the series has five lead characters: King Viserys Targaryen (Considine), Alicent Hightower (Cooke), Princess Rhaenyra Targaryen (D’Arcy), Prince Daemon Targaryen (Smith) and Lord Corlys Velaryon (Toussaint), known as the Sea Snake, who becomes Hand to Queen Rhaenyra Targaryen during the Dance of the Dragons.

Toussaint’s Lord of House Velaryon comes from a Valyrian bloodline as old as House Targaryen. As “The Sea Snake,” the most famed nautical adventurer in the history of Westeros, Lord Corlys built his house into a powerful seat that is even richer than the Lannisters and that claims the largest navy in the world. Danny Sapani was previously in talks for the role.

Best is cast as Princess Rhaenys Velaryon. A dragonrider and wife to Lord Corlys Velaryon, “The Queen Who Never Was” was passed over as heir to the throne at the Great Council because the realm favored her cousin, Viserys, simply for being male.

House of the Dragon was co-created by Martin and Condal. The pilot script that landed the series order was written by Condal. He serves as co-showrunner alongside GoT veteran Miguel Sapochnik, who will direct the pilot and additional episodes. Martin, Condal and Sapochnik executive produce alongside writer Sara Lee Hess, Vince Gerardis and Ron Schmidt. Greg Yaitanes co-executive produces. Yaitanes, Clare Kilner and Geeta V. Patel round out the 10-episode series’ directing team.

On stage, Best has been honored with the Evening Standard Award for Outstanding Newcomer in Tis Pity She’s A Whore, and the Olivier Award for Best Actress playing the title role in Hedda Gabler. On Broadway she received Tony nominations for the revivals of A Moon for the Misbegotten and The Homecoming. In television and film Best is known for her roles in Nurse Jackie, The Honorable Woman and The King’s Speech. Best is represented by Independent Talent Group and ICM Partners.

Deadline