It seems like every few weeks, a spin-off series is announced that further expands the "Game of Thrones" universe. In addition to upcoming projects such as the animated series "Nine Voyages," the untitled Jon Snow TV show starring Kit Harington, and the second season of "House of Dragons," a prequel series centered on a certain Targaryen ruler is planned.

Last week, HBO is developing a series based on Aegon the Conqueror, the founder and first king of the Targaryen dynasty who conquered the continent of Westeros and unified the kingdom with his sister wives, Rhaenys and Visenya, and their three dragons, Balerion, Vergar and Meraxes Aegon the Conqueror.

Fans of the "Game of Thrones" prequel series "House of the Dragon" must have heard of Aegon Targaryen, and the HBO show will star Prince Aegon II (played by Tom Glynn-Kearney), King Aegon's godson and great-grandson, as well as Aegon's son, Aegon II. The show is about the "Dance of Dragons" succession battle between Prince Aegon II (played by Tom Glynn-Kearney), Aegon's godson and great-grandson, and Princess Rhaenyra Targaryen (played by Emma Darcy), Aegon II's half-sister. To add to the confusion, Rhaenyra also named one of her sons after the O.G. King of the Iron Throne, and the young Aegon III is played in "HOTD" by twin child actors Jake and Rory Hurd.

But while I've heard of Aegon Targaryen, I've never seen him on screen; according to The Hollywood Reporter, the "Aegon's Conquest" spinoff will be a direct prequel to "House of Dragons," and will feature Aegon Targaryen's Seven Kingdoms The story is said to be about "Aegon Targaryen's bloody and brutal conquest of the Seven Kingdoms." It is said to take place a century before "HOTD. (If you're wondering, "House of the Dragon" itself takes place almost 200 years before "Game of Thrones.")

THR reports that the Aegon-focused show will take a "back-to-basics" approach to George R.R. Martin's fantasy world, and HBO has already tapped screenwriter Mattson Tomlin. He did uncredited work on Matt Reeve's "Batman" and co-wrote the upcoming sequel "Batman Part II."

Given that "House of the Dragon" Season 2 is already scheduled to be delivered in summer 2024 (by series star Matt Smith) and that HBO just announced about a prequel to the "House of the Dragon," "Aegon the Conqueror" series will not be seen until 2025 or 2026 at the earliest.

But this is not the only "Game of Thrones" spinoff in development. (And that doesn't even include now-defunct shows like the prequel series that never got made.) In addition to series like the aforementioned "Nine Voyages" and the Jon Snow-focused spin-off, there is also "A Knight Of The Seven Kingdoms": based on Martin's novel "Dunk and Egg" : The Hedge Knight", which is also set to become a series and will reportedly begin production this year.

Tom's Guide will keep you updated on news regarding the Aegon the Conqueror prequel and other "Game of Thrones" related projects currently in development by HBO. In the meantime, Westeros fans can revisit both "Game of Thrones" and "House of Dragons" with a Max subscription.