Another Game of Thrones prequel series is in the works at HBO, this one based on author George R. R. Martin's Tales of Dunk and Egg fantasy novella series. Variety reports that the one-hour series would follow the adventures of Ser Duncan the Tall (Dunk) and a young Aegon V Targaryen (Egg) 90 years prior to the events of A Song of Ice and Fire, which was what the original TV series was based on.

There are three installments of the Tales of Dunk and Egg series to date: The Hedge Knight, published in 1998; The Sworn Sword, published in 2003; and The Mystery Knight, published in 2010. After initially selling separately, the three titles have since been compiled to be published together as A Knight of the Seven Kingdoms in 2015. Although the source material is much more limited, it's not clear if HBO will develop Tales of Dunk and Egg as a miniseries or an ongoing show that surpasses the timeline of the original books.

Tales of Dunk and Egg is gearing up for development, but the prequel hasn't yet officially been ordered to series. It's still possible the project will get shelved before making it to production, as this was the case for another Game of Thrones prequel show that was in the works. Led by Naomi Watts, a prequel titled Bloodmoon had gotten as far as actually shooting the pilot episode for a new series set 10,000 years before Game of Thrones. For reasons unknown, HBO axed the show after seeing the pilot, and it's not clear if the footage will ever see the light of day.

Meanwhile, production on another prequel series, House of the Dragon, appears to be moving along much better. The spinoff was ordered straight to series in 2019, based on Martin's material from Fire and Blood with the first season spanning ten episodes. The writing process has begun and significant castings so far include Paddy Considine as Viserys Targaryen the First, Olivia Cooke as Alicent Hightower, Emma D'Arcy as Rhaenyra Targaryen, and Matt Smith as Daemon Targaryen. Set 300 years before its parent series and following the rise of House Targaryen, the prequel is expected to arrive sometime in 2022.

Game of Thrones was a smash hit for HBO, scoring big at awards season consistently while earning very positive reviews from critics and viewers alike. Unfortunately, the final season left many fans feeling unsatisfied, drawing about great criticism and even spawning a petition to remake the last season from scratch. The experience might make it difficult for some of these fans to trust investing in another Game of Thrones series, but even though it had a rocky landing, the overall success of the original show cannot be denied.

There's no word yet on when production on Tales of Dunk and Egg might start, and no writers or cast members are currently attached. However, HBO is reportedly considering the prequel to be a high priority as the cabler looks to bring back many fans of Game of Thrones that unsubscribed to the network after the show's final season, amid reports of HBO losing more than half of its viewers. We'll see if Tales of Dunk and Egg or House of the Dragon gets them to return. This news was first reported by Variety.