The photos feature Olivia Cooke as Alicent Hightower alongside Rhys Ifans as Otto Hightower, while another shows Steve Toussaint, as Corlys Velaryon.
Paddy Considine, Eve Best, Sonoya Mizuno and Fabien Frankel also star.
HBO described Rhaenyra Targaryen as "the king's first-born child, she is of pure Valyrian blood, and she is a dragonrider. Many would say that Rhaenyra was born with everything … but she was not born a man."
Daemon Targaryen: "The younger brother to King Viserys and heir to the throne. A peerless warrior and a dragonrider, Daemon possesses the true blood of the dragon. But it is said that whenever a Targaryen is born, the gods toss a coin in the air."
Otto is the Hand of the King to the current ruler of Westeros, King Viserys Targaryen.
"Ser Otto loyally and faithfully serves both his king and his realm," according to HBO's character description.
"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."
Alicent is described by HBO as "the most comely woman in the Seven Kingdoms". She was raised in the Red Keep, in King's Landing, "close to the king and his innermost circle; she possesses both a courtly grace and a keen political acumen".
The final image shows Steve Toussaint as Lord Corlys of House Velaryon, known as the Sea Snake.
Corlys and his family are from a "Valyrian bloodline as old as House Targaryen", said HBO. "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."
Game of Thrones' 10th anniversary was marked in Australia by a slew of GoT content - including a reunion featuring the cast - on Foxtel.
House of the Dragon will premiere on Foxtel in Australia in 2022.
