'Game of Thrones' Prequel 'House of the Dragon' Gets Premiere, Character Guide, First Photos From HBO

A little more than three years after Game of Thrones came to an end on HBO, its prequel will premiere: House of the Dragon debuts Aug. 21 (although no specific time has been announced yet).

House of the Dragon is a 10-episode drama series that will also stream on HBO Max. It is based on author George R.R. Martin's Fire & Blood and set 200 years before the events of Game of Thrones, telling the story of House Targaryen. It hails from co-creator and co-showrunners Ryan Condal and Miguel Sapochnik and co-creator and executive producer Martin, with Sara Hess service as executive producer and writer, and Jocelyn Diaz, Vince Gerardis, and Ron Schmidt serving as executive producers. Greg Yaitanes is a co-executive producer and director, and Clare Kilner and Geeta V. Patel are directors.

Game of Thrones became a "Metacritic must-watch" series, earning an 86 Metascore for its eight seasons. It also won numerous awards during its tenure, including a whopping 59 Primetime Emmy Awards.

Read below for HBO's official character descriptions, including the actors who play them, and see some first looks at them as well.

Paddy Considine as King Viserys Targaryen, chosen by the lords of Westeros to succeed the Old King, Jaehaerys Targaryen, at the Great Council at Harrenhal. HBO calls him "a warm, kind, and decent man," noting his "only wish is to carry forward his grandfather's legacy. But good men do not necessarily make for great kings."

Matt Smith as Prince Daemon Targaryen, King Viserys' younger brother and heir to the throne. He is called "a peerless warrior and a dragonrider" who 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...

Olivia Cooke as Alicent Hightower, the daughter of Otto Hightower, the Hand of the King. She is described as "the most comely woman in the Seven Kingdoms." Raised in the Red Keep, she is close to the king and his innermost circle, and possesses both a courtly grace and a keen political acumen.

Emma D'Arcy as Princess Rhaenyra Targaryen, the king's first-born child, who is of pure Valyrian blood and a dragonrider. She is described as having been born with everything, but not being born a man, which puts her at disadvantages outside of her control.

Steve Toussaint as Lord Corlys Velaryon, "The Sea Snake." From the Lord of House Velaryon, a Valyrian bloodline as old as House Targaryen, he is the most famed nautical adventurer in the history of Westeros. HBO says, "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."

Eve Best as Princess Rhaenys Targaryen, a dragonrider and Lord Corlys Velaryon's wife. She is known as "The Queen Who Never Was" because she was passed over as heir to the throne at the Great Council because the realm favored her cousin, Viserys, simply for being male.

Fabien Frankel as Ser Criston Cole, of Dornish descent, Lord of Blackhaven's steward's common-born son who has no claim to land or titles — just his name, which is his honor, and his preternatural skill with a sword.

Sonoya Mizuno as Mysaria, who came to Westeros with nothing, sold more times than she can recall. HBO says, "She could have wilted, but instead she rose to become the most trusted — and most unlikely — ally of Prince Daemon Targaryen, the heir to the throne."

Rhys Ifans as Otto Hightower, The Hand of the King, who loyally and faithfully serves both his king and his realm. As he sees it, the greatest threat to the realm is the king's brother, Daemon, and his position as heir to the throne.

Milly Alcock as Young Princess Rhaenyra Targaryen, played in later adulthood by D'Arcy. 

Emily Carey as Young Alicent Hightower, played in later adulthood by Olivia Cooke.

Bethany Antonia as Baela Targaryen, Laena Velaryon's oldest daughter and the rider of the young dragon Moondancer.

Phoebe Campbell as Rhaena Targaryen, Lady Laena's second daughter and Baela's sister.

Harry Collett as Jacaerys Velaryon, Rhaenyra Targaryen's oldest son.

Ryan Corr as Ser Harwin 'Breakbones' Strong, Master of Laws Lyonel Strong's oldest son and Harrenhal's heir. He is believed to be "the strongest man in the Seven Kingdoms."

Tom Glynn-Carney as Aegon Targaryen, King Viserys' first-born son.

Jefferson Hall as Tyland Lannister, described as "a crafty and calculating politician" and Lord Jason Lannister's twin.

Jefferson Hall as Lord Jason Lannister, the Lord of Casterly Rock and Ser Tyland Lannister's twin.

David Horovitch as Grand Maester Mellos, described as "a voice of reason and trusted advisor to King Viserys."

Wil Johnson as Ser Vaemond Velaryon, Coryls Velaryon's brother and a Velaryon navy commander.

John Macmillan as Ser Laenor Velaryon, Corlys Velaryon and Rhaenys Targaryen's son.

Graham McTavish as Ser Harrold Westerling, who has served in the Kingsguard since the days of King Jaehaerys. He's described as "a paragon of chivalry and honor."

Ewan Mitchell as Aemond Targaryen, Viserys' second-born, Daemon's nephew, and Rhaenyra's half-brother.

Theo Nate as Ser Laenor Velaryon, Corlys Velaryon and Rhaenys Targaryen's son.

Matthew Needham as Larys Strong, Master of Laws Lyonel Strong's young son, who is brought to court by his father.

Bill Paterson as Lord Lyman Beesbury, Lord of Honeyholt and Master of Coin on King Viserys's small council.

Phia Saban as Helaena Targaryen, Viserys' second-born daughter, Aegon and Aemond's sister, and Rhaenyra's half-sister.

Gavin Spokes as Lord Lyonel Strong, Master of Laws to King Viserys and Lord of Harrenhal.

Savannah Steyn as Lady Laena Velayron, Corlys Velaryon and Rhaenys Targaryen's daughter.