HBO's 'House of the Dragon' has added some more actors into its arsenal.

Matt Smith, Paddy Considine, Olivia Cooke, and Emma D’Arcy will have some more familiar faces joining their ranks in the 'Game of Thrones' prequel series. Welsh actor Rhys Ifans will be joining the cast, as well as some more recognisable faces.

The straight-to-series 'House of the Dragon' will feature the 'Notting Hill' and 'Harry Potter' actor as a character named Otto Hightower, according to Deadline. According to the publication, he will be the Hand of the King Viserys: "Ser Otto loyally and faithfully serves both his king and his realm. As the Hand sees it, the greatest threat to the realm is the king’s brother, Daemon, and his position as heir to the throne."

Alongside Ifans will be Steve Toussaint, who has had minor roles in a number of British series over the years including 'Skins', 'Doctors', and Russell T. Davis' 'It's a Sin'. He also starred in 'Prince of Persia: The Sands of Time'. He'll play the role of Lord Corlys Velaryon, known as the Sea Snake.

Eve Best has been confirmed in the cast line-up, an actress who has starred in 'Nurse Jackie' and Netflix's newest fantasy release 'Fate: The Winx Saga'. She'll play Viserys cousin, Princess Rhaenys Velaryon, a dragon rider and wife to Lord Corlys Velaryon.

Actress Sonoya Mizuno will also join 'House of the Dragon', who has starred in the TV mini-series 'Devs', 'Maniac', and 'Crazy Rich Asians'. She's been cast as a woman named Mysaria, who is a slave who becomes an ally of Prince Daemon Targaryen.

The 'Game of Thrones' prequel will be based on the 'Fire & Book' books from George R.R. Martin, which is set roughly 300 years before the events of what we've seen on screen so far. The book tells the full lineage of the House of Targaryen with King Viserys Targaryen being played by Paddy Considine, Prince Daemon Targaryen by Matt Smith, Alicent Hightower by Olivia Cooke, and Princess Rhaenyra Targaryen by Emma D’Arcy. The series will debut on HBO Max in 2022 (and presumedly Sky Atlantic over here).