Viewers couldn't believe how this Game of Thrones actress transformed for BBC drama The Moorside

Here’s a twist not even the hardiest Game of Thrones book fans could have predicted: Yara Greyjoy plays Karen Matthews. Well, actress Gemma Whelan, best known as the most dangerous woman on the Iron Islands, can be spotted as Shannon Matthews' mum in chilling BBC drama The Moorside.

However, many viewers found her pretty hard to recognise with her northern accent and clever make-up job…

But they’re forgetting: 35-year-old Whelan is a chameleon on screen, having starred as Veronica in BBC3 sitcom Uncle, as well as appearing in Morgana Robinson’s The Agency last year.

She’s also an accomplished stand-up, having won a Funny Women Variety Award in 2010.

And that wasn’t the only familiar face hidden away last night: Sherlock’s Sian Brooke also starred as Natalie Brown in The Moorside. The Matthews' concerned neighbour has the same face as Eurus Holmes, Culverton Smith’s daughter, Watson’s psychologist and his mistress.

Think you’ve spotted another famous face? Check more details about The Moorside’s cast and characters here.