Game of Thrones spin-off based on House Targaryen reportedly in the works

The rumoured new spin-off will be set 300 years prior to the events of the hit fantasy series Game of Thrones (pictured). Image / YouTube, HBO

A prequel to Game of Thrones has just wrapped filming, but HBO is reportedly planning another spin-off, and it's going to make fans very happy.

First piece of good news; you can expect a lot of dragon action.

Deadline reports HBO is close to giving a pilot order to another GoT prequel, which is set 300 years before the events of the hit fantasy series and is set to focus on the rise and fall of House Targaryen.

It is based on the book Fire & Blood, written by GoT author George R.R. Martin, who is also on-board to produce the project, the website claimed.

Another unnamed prequel, which is set tens of thousands of years before the events of GoT and chronicles the beginning of the White Walkers, has just finished shooting a pilot in Italy.

Written by Jade Goldman, it stars Australian actor Naomi Watts in the lead role as a "socialite with a dark secret".

If it is greenlit — which it no doubt will be — the series is expected to drop some time next year.

Naomi Watts plays the lead role in another unnamed Game of Thrones prequel which has just wrapped shooting in Italy. It's expected to debut next year if greenlit. Photo / Getty Images

But news of this new prequel will be particularly exciting for fans, given it's not too far removed from the characters we have come to know and love.

Game of Thrones, which is available to stream on Neon, touched on the fascinating history of House Targaryen, but by the end of the show, which aired its eighth and final season in May, it had almost died out.

The new series will explore the height of the Targaryens' power after Jon Snow and Daenerys' ancestor, Aegon the Conqueror, invaded Westeros with his dragons and united it under the Iron Throne, becoming the first Lord of the Seven Kingdoms.

The book details how Aegon united the Seven Kingdoms because he predicted Westeros would need to defend itself from the White Walkers.

The series will be based on George R. R. Martin's book Fire & Blood and Martin will also produce the project, according to Deadline. Photo / Supplied

You can also anticipate some weird incest shenanigans, with Aegon having married both of his sisters, Visenya and Rhaenys. And we thought Jon and Dany being aunty and nephew was gross.

Martin wrote a blog post in May confirming there were several other shows in development, hinting one based on Fire & Blood would be one.