Milly Alcock is an Australian actor who has appeared primarily in Australian productions before now, including Janet King, A Place to Call Home, Pine Gap, and Upright. Her portrayal of the young Rhaenyra Targaryen is one of the highlights of House of the Dragon.
Emma D'Arcy will play the aged-up version of Rhaenyra after the show does a time jump. Before House of the Dragon, Emma appeared in shows like Wanderlust, Truth Seekers, and Hanna.
Emily Carey is the picture of innocence as young Alicent. This is perhaps Emily's biggest role to date; she previously appeared in series like Get Even and Casualty.
Taking over the role of Alicent after the time jump is Olivia Cooke, whom you might know from Bates Motel, Vanity Fair, and Me and Earl and the Dying Girl.
Paddy Considine looks quite different with his platinum Targaryen wig. He has extensive screen credits pre–House of the Dragon, including roles in Peaky Blinders, The Third Day, and The Outsider
Sian Brooke's time onscreen as Aemma Arryn was short but significant. She has also appeared in shows like Good Omens and Sherlock.
Rhys Ifans's eclectic career includes roles in Notting Hill, Harry Potter and the Deathly Hallows, and Spider-Man: No Way Home, and his take on Otto Hightower is delightfully calculating.
Sonoya Mizuno is intriguing as the mysterious Mysaria. You might remember the actor from Maniac or Crazy Rich Asians.
After the first episode of House of the Dragon, Steve Touissant quickly emerged as a fan favorite in the role of Corlys Velaryon. His prior credits include Pine Gap, Doctor Who, and Prince of Persia: The Sands of Time
Eve Best forms the other part of Westeros's current power couple as Rhaenys Velaryon. Previously she's appeared in Nurse Jackie and The King's Speech.
The handsome Fabien Frankel plays the handsome Criston Cole. You might have seen him in The Serpent before this.
Graham McTavish has been in The Hobbit and Outlander and is now bringing his Scottish accent to Harrold Westerling of the Kingsguard in House of the Dragon.