A Game of Thrones prequel movie is in the works.

Beau Willimon — who has worked on shows including House of Cards and Star Wars spin-off Andor — has been tapped to write the script for the film that is in development at Warner Bros.

A recent Hollywood Reporter cover story with Game of Thrones author George RR Martin teased that the picture will be a "Dune-sized feature film" that is based on King Aegon Targaryen's conquest of Westeros — which united six of the seven kingdoms around 300 years before the events of the Game of Thrones pilot episode.

HBO is also developing a TV series that is inspired by the exact same story.

Numerous spin-off projects have come to fruition since Game of Thrones ended on the small screen in 2019. 

The prequel series A Knight of the Seven Kingdoms premiered earlier this year, while season three of House of the Dragon is set to arrive on screens in June.

Warner Bros. involvement comes at an uncertain time for the studio following its recent US$110 billion (S$140 billion) acquisition deal by Paramount Skydance.

Paramount CEO David Ellison has promised that the deal will "honour the legacy of two iconic companies while accelerating our vision of building a next-generation media and entertainment company".