Everyone’s favorite television epic, Game of Thrones, came to a controversial end on May 19. The fantasy series reigned supreme as the most popular show in the world for years and the finale episode became the most-watched show in HBO’s history.

But HBO, high on the success of the show, is already plotting several spinoffs. George R.R. Martin, who wrote the Song of Ice and Fire series on which Game of Thrones is based, has said on his blog that five potential Game of Thrones shows are in the works. So far, one Game of Thrones prequel has begun production in Northern Ireland. A second prequel, centered on Daenerys Targaryen’s ancestors, is in development at the network.

HBO executives have hinted that even more prequels, sequels and spinoffs could be on the way. Here’s what you need to know.

What Game of Thrones spinoffs are in the works?

HBO initially hired writers to work on five different Game of Thrones spinoffs. In May 2017, Martin wrote on his blog that every single script under consideration was set long before the rise of Daenerys Targaryen. “Every one of the concepts under discussion is a prequel, rather than a sequel. Some may not even be set on Westeros. Rather than ‘spinoff’ or ‘prequel,’ however, I prefer the term ‘successor show.’ That’s what I’ve been calling them.”

So far, it looks like HBO is moving forward with two of these ideas. The first yet-to-be-named prequel comes from a story by Martin and showrunner Jane Goldman, who wrote the screenplays for Kick-Ass, X-Men: First Class and Kingsman: The Secret Service. It will center on characters from the Westerosi Age of Heroes, including Stark ancestor Bran the Builder.

The second project will be based on Martin’s Fire and Blood book, a comprehensive history of how House Targaryen conquered Westeros with the aid of dragons. The show would be set 300 years before Game of Thrones. Martin — who is still in the process of finishing the Song of Ice and Fire book series upon which the Game of Thrones television show was based — is co-writing the pilot with Colony executive producer Ryan Condol, according to Deadline.

What is the first Game of Thrones prequel about?

Martin has written on his blog that he thinks the show should be called The Long Night. That name tells fans exactly what the Game of Thrones prequel is about. The Long Night refers to a period of time in Westeros’ history, about 5000 years before the events of Game of Thrones, during the Age of Heroes. Winter and darkness descended on the land and lasted an entire generation. (“The Long Night” was also the name of a recent episode of Game of Thrones that highlighted the battle between the living and the dead.)

During this time, the White Walkers entered Westeros from the North. Humans were driven southward by their advance. Eventually, humans allied with the Children of the Forest to fight the White Walkers, and the first members of the Night’s Watch drove the wights back during The Battle for the Dawn. In order to protect humans in the future, Bran the Builder, a Stark ancestor, raised the Wall using ice and magic.

But just because that’s the history that characters know in Martin’s books and the HBO show, doesn’t mean that’s how events actually played out. The men and women of that time period have reached legendary status by the time that Old Nan is relaying their stories to Bran Stark, and their accomplishments may have been exaggerated or even fabricated. HBO has promised that the true history of Westeros is “not the story we think we know.”

Martin has since clarified that the show may not be titled The Long Night since the third episode of season eight of Game of Thrones had that title. “I heard a suggestion that it could be called The Longest Night, which is a variant I wouldn’t mind,” he told Entertainment Weekly.

Are the Starks, Lannisters and other great houses in the show?

The finale of Game of Thrones proved that the show was really about the Stark family all along. And George R.R. Martin recently assured Entertainment Weekly that both the Starks and their trusty direwolves would play a major role in the prequel series. “The Starks will definitely be there,” he said.

The Lannisters, however, will not be a part of the show — or at least not the first episode. “The Lannisters aren’t there yet, but Casterly Rock is certainly there,” Martin said, referencing the Lannister’s future domicile. “It’s actually occupied by the Casterlys — for whom it’s still named after in the time of Game of Thrones.” In Martin’s books, legend has it that Lann the Clever, founder of House Lannister, swindled the Casterlys out of their home. It’s likely that fans will get to see this story play out in the prequel.

Martin said that at the time of the prequel, Westeros is divided into about 100 kingdoms. Essentially, that means that our new heroes must survive in a chaotic land with no consolidated power. “We talk about the Seven Kingdoms of Westeros; there were Seven Kingdoms at the time of Aegon’s Conquest,” Martin said. “But if you go back further then there are nine kingdoms, and 12 kingdoms, and eventually you get back to where there are a hundred kingdoms — petty kingdoms — and that’s the era we’re talking about here.”

Are White Walkers, Dragons or other fantastical creations on the show?

Some fans will be disappointed to hear that the show takes place before the Targaryens came to power, which means the story also predates dragons. However, without dragons eating up the show’s CGI budget, maybe that means a bigger role for the direwolves.

Martin says that other creatures like mammoths will be present. And, of course, there’s the threat of the White Walkers who marched on the First Men long before they confronted Jon Snow. “Obviously the White Walkers are here — or, as they’re called in my books, the Others — and that will be an aspect of it,” said Martin.

Who is in the Game of Thrones prequel cast?

HBO has released only a few details about the Game of Thrones prequel cast. Martin has said that the show, like Game of Thrones, is a “large ensemble.” Here’s who is attached so far.

Naomi Watts

Naomi Watts attends Build to discuss her new film 'The Book Of Henry' at Build Studio on May 17, 2017 in New York City. Desiree Navarro—WireImage

The Mulholland Drive and Birdman actor is the biggest star attached to the project. She will play a noblewoman hiding many secrets. Fans are already theorizing that she’s a Lannister ancestor, plotting to ascend to power.

Josh Whitehouse

Josh Whitehouse attends the Virgin TV British Academy Television Awards ceremony at the Royal Festival Hall on May 13, 2018 in London, United Kingdom. Barcroft Media via Getty Images

Whitehouse, one of the stars of the television show Poldark, will play a member of House Stark. It’s possible he plays Bran the Builder, who according to legend built both the Wall and Winterfell.

Naomi Ackie

Naomi Ackie attends 'Lady Macbeth' photocall during 64th San Sebastian International Film Festival at Kursaal Palace on September 19, 2016 in San Sebastian, Spain. Carlos Alvarez—Getty Images

Ackie—who starred in the film Lady Macbeth and is set to appear in Star Wars: Episode IX—will play an unnamed character in the new show.

Denise Gough

Irish actress Denise Gough attends the Premiere of "Colette" during the Toronto International Film Festival, on September 11, 2018, in Toronto, Ontario, Canada. Valerie Macon—AFP/Getty Images

The actor — who recently appeared in a Tony-winning production of Angels in America, and gave voice to Yennefer in the popular video game Witcher 3 — will play a yet-to-be-named character on the show.

Jamie Campbell Bower

Jamie Campbell Bower attends the HUGO show during the Berlin Fashion Week Spring/Summer 2019 at Motorwerk on July 5, 2018 in Berlin, Germany Gisela Schober—Getty Images

Campbell Bower, who appeared in Fantastic Beasts: The Crimes of Grindelwald and the Twilight films, has been cast in the show.

Sheila Atim

Sheila Atim receives the award for Best Actress In A Supporting Role In A Musical for 'Girl From The North Country' on stage during The Olivier Awards with Mastercard at Royal Albert Hall on April 8, 2018 in London, England. Jeff Spicer—Getty Images

The stage actress, best known for her award-winning turn in Girl From The North Country, stars as a yet-unnamed character.

Ivanno Jeremiah

Ivanno Jeremiah arrives for the South Bank Sky Arts Awards at the Savoy Hotel on June 5, 2016 in London, England. John Phillips—Getty Images

The Humans and Black Mirror actor plays an unnamed character in the Game of Thrones prequel.

Georgie Henley

Georgie Henley, attend the red carpet at the Edinburgh International Film Festival for the premier of "Access All Areas" at Cineworld on June 30, 2017 in Edinburgh, Scotland. Barcroft Media via Getty Images

The Chronicles of Narnia actor will play an unannounced character in the show.

Alex Sharp

Alexander Sharp poses at the opening night of the Roundabout Theatre Company's production of Sam Shepard's "True West" on Broadway at The American Airlines Theatre on January 24, 2019 in New York City. Bruce Glikas—FilmMagic

The star of How to Talk to Girls at parties will also star in the series.

Toby Regbo

oby Regbo attends The CW's "Reign" exclusive premiere screening and panel during Comic-Con International 2014 at the San Diego Convention Center on July 24, 2014 in San Diego, California. Ethan Miller—Getty Images

Another Crimes of Grindelwald alum, Regbo will also star in the series.

Marquis Rodriguez

Actor Marquis Rodriguez attends the 2017 New York Latino Film Festival "Saturday Church" opening night screening at Cineopolis Chelsea on October 11, 2017 in New York City Daniel Zuchnik—Getty Images

Rodriguez starred in the Netflix shows Luke Cage and Iron Fist and appears in Ava DuVernay’s miniseries about the Central Park Five, When They See Us. He will play an unknown character in the Game of Thrones prequel.

John Simm

John Simm at the 2017 Winter TCA Tour for Disney/ABC Greg Doherty—Getty Images

John Simm is best known as a stage actor in London but also played the Master on Doctor Who and starred in Life on Mars. HBO has not yet announced what character he will play in the new show.

Richard McCabe

Richard McCabe, winner of Best Actor in a Supporting Role, poses in the press room at The Laurence Olivier Awards 2013 at The Royal Opera House on April 28, 2013 in London, England. Dave M. Benett—Getty Images

Theater actor Richard McCabe won accolades, including a Tony and the Olivier Award, for his work in Peter Morgan’s play about Queen Elizabeth starring Helen Mirren, The Audience. HBO has not yet said who he will play in the prequel.

John Heffernan

LONDON, ENGLAND - APRIL 11: John Heffernan attends the UK premiere of "Eye In The Sky" on April 11, 2016 in London, United Kingdom. (Photo by Anthony Harvey/Getty Images) Anthony Harvey—Getty Images

Heffernan has worked with the Royal Shakespeare Company and National Theater in England and also starred in episodes of Luther and The Crown. It is not yet known who he will play in the HBO show.

Dixie Egerickx

Egerickx is only 13 years old but has already starred in Patrick Melrose and The Little Stranger. It’s not yet clear who she will portray in the prequel.

Are any Game of Thrones characters in the prequel?

Because the prequel is set about 5,000 years before the execution of Ned Stark, none of the current show’s actors — including Emilia Clarke, Maisie Williams, Kit Harington and Sophie Turner — will become a part of the Game of Thrones prequel cast. The one exception could be the Night King, played by Vladimír Furdík on Game of Thrones.

What is the second prequel about?

HBO is planning a second prequel that will focus on the dragon-riding Targaryens. Fire & Blood, the book upon which the script is based, begins with Aegon the Conqueror taking over Westeros and creating the Iron Throne. It then proceeds to retell the story of each generation of Targaryen ruler who fought to maintain his or her rule. The story includes the civil war known as the Dance of Dragons that pitted Targaryen against Targaryen.

The show would be set hundreds of years before Game of Thrones, so it’s unlikely that Emilia Clarke, who portrayed Daenerys on the show, would return for the series.

Is the story of Game of Thrones over?

The stories of Daenerys Targaryen and Jon Snow came to an end in the final episode of Game of Thrones. But the prequel will likely add context to the current character’s tales. As Martin has written, the history is not necessarily what readers expect it to be — or what the current characters believe to be true.

The Long Night plot, as described by Martin in the books, closely mirrors the plot of the current Game of Thrones TV show: The White Walkers invade. A human hero emerges to stop them. Hopefully, when HBO says that the story of the Long Night isn’t the one we think we know, that means Goldman will be free to create new yarns rather than remixing the tried and true formula.

Stories like that of Bran the Builder could add new layers to the experiences of his namesake Bran or the other Starks. Plus, fans may finally be able to see the fabled Ice Spiders from Old Nan’s stories.

Do we have a Game of Thrones prequel release date yet?

We don’t know the release date of either of the new shows yet, but this story will be updated once HBO releases that information.

Do we have a Game of Thrones prequel trailer yet?

We do not yet have a trailer for either prequel. But HBO did tell Entertainment Weekly that they plan to begin production of the show early this summer.

Is there a Game of Thrones prequel book?

Martin has published prequels to the Game of Thrones series, novellas and in-work histories. But none focus on the Long Night as the first upcoming show will.

However Fire and Blood: 300 Years Before Game of Thrones, about the rise and reign of the Targaryen family (Daenerys’ family members), will serve as a template for the second prequel that’s in the works.

Martin has also published a series of prequel novellas called The Tales of Dunk and Egg that take place about 90 years before the events of his Song and Ice and Fire series upon which Game of Thrones is based. In those books, two knights travel through Westeros.

Who is making the show?

Martin collaborated with Goldman on the script for the Naomi Watts-led prequel. Unlike Game of Thrones, the Long Night show is based on tidbits from Martin’s books and blog, not an actual series of novels, so Martin was likely instrumental in providing history and context to Goldman. Goldman, for her part, has cut her teeth on genre television with human dramas like X-Men.

Jessica Jones director S.J. Clarkson will film the project’s first episode and also serve as an executive producer.

Martin is also reportedly working on the second prequel, this time with TV vet Ryan Condol.

How many episodes are there in the Game of Thrones prequel?

HBO has not yet announced how many episodes they plan to film of either show. The first six seasons of Game of Thrones contained 10 episodes, and the last two seasons had seven and six, respectively.

Write to Eliana Dockterman at eliana.dockterman@time.com.