Josh Whitehouse is joining the cast of the "Game of Thrones" prequel.
The Hollywood Reporter said the British actor will play a key role in the series but not the male lead. Details about his character are being kept under wraps.
Whitehouse confirmed his casting in an Instagram post Wednesday.
"So I've been holding on to some very big news and it's been killing me - but here you go #gameofthrones," he wrote.
The new show was the first of several "successor series" to be picked up to pilot and is set thousands of years before the events of "Game of Thrones."
"Game of Thrones" is based on the George R.R. Martin book series "A Song of Ice and Fire."
Whitehouse plays Hugh Armitage on "Poldark," which completed a fourth season on BBC One in July.