GeekTyrant reports HBO just cast two more actors for its upcoming Game of Thrones prequel, titled House of the Dragon – Olivia Cooke and Matt Smith. Cooke appeared on TV shows Bates Motel and Vanity Fair. She also played a supporting role in Steven Spielberg’s adaptation of Ready Player One and the female lead in the horror-thriller The Limehouse Golem. Smith is by far best known for his performance as the eleventh Doctor in BBC’s sci-fi series Doctor Who and his role as Prince Phillip in the Netflix period drama The Crown.

Even before Game of Thrones aired its finale last year, HBO has already been working on several possible spinoffs. One of them was for a show set thousands of years ago in the mythical past of Westeros, developed by the screenwriter Jane Goldman (Kick-Ass, X-Men: First Class). That project, however, has since been abandoned. The surviving prequel series is based on George R. R. Martin’s book Fire and Blood that chronicles the civil war among the members of the Targaryen royal dynasty.

Cooke and Smith will join cast members Emma D’Arcy (Hanna, Truthseekers) and Paddy Considine (The Outsider, Hot Fuzz). Cooke will play Alicent Hightower, daughter to the Hand of the King. Smith will portray prince Daemon Targaryen, younger brother to the king and heir to the throne. Considine will play the role of the king Viserys while D’Arcy will portray Princess Rhaenyra Targaryen, one of the instigators of the war. Currently, HBO is in talks with the actor Danny Sapani (Penny Dreadful). The pilot was written by Ryan J. Condal (Hercules, Rampage) and will be directed by the veteran TV director Miguel Sapochnik.