LOS ANGELES• Naomi Watts heard it was "Game over" for her on Tuesday.
Hollywood publications reported that cable channel HBO had scrapped plans for a Game Of Thrones prequel starring her.
A pilot was shot in Northern Ireland earlier this year, with the story set thousands of years before the events covered in Game Of Thrones.
Mr Casey Bloys, president of programming at HBO, told reporters in July after filming finished on the pilot episode that he was pleased with what he had seen.
"It looks really good. The cast was amazing," he said at a Television Critics Association event in Beverly Hills.
But HBO has now opted to back another venture, ordering 10 episodes of a Game Of Thrones spin-off called House Of The Dragon.
House will take place 300 years before the events of Game Of Thrones, a mediaeval fantasy series that became a global phenomenon before it ended its eight-season run in May.
The new series will be based on George R.R. Martin's book Fire & Blood and will tell the story of House Targaryen, HBO said.
The network announced the new show on Tuesday at an event intended to stir up enthusiasm for HBO Max, a streaming service that will launch in May next year at US$15 (S$20.40) a month to compete with Netflix and Walt Disney.
HBO did not say when House would become available.
The final season of Game Of Thrones won 12 Emmy awards, including the top prize of best drama series, last month.
The pilot for the prequel was one of several Game Of Thrones-related projects that were put into development at HBO prior to the end of the series.