Game of Thrones prequel adds 'Doctor Who' actor John Simm and more

HBO has added several new cast members to its eagerly-anticipated Game of Thrones prequel series, including Life on Mars actor John Simm.

The 48-year-old is certainly no stranger to shows with built-in fandoms, nor is he to sci-fi fantasy shows themselves, having played renegade alien Time Lord The Master in Doctor Who from 2007 to 2017.

According to Deadline, The Crown‘s John Heffernan and Dixie Egerickx, who most recently appeared alongside Ruth Wilson and Domhnall Gleeson in supernatural chiller The Little Stranger, have also been added to the ever-expanding roster. Wallander and Peaky Blinders actor Richard McCabe rounds out the latest batch of new faces.

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They will all join existing cast members Josh Whitehouse (Poldark), Naomi Ackie (Lady Macbeth), Miranda Richardson (Harry Potter and the Goblet of Fire), Ivanno Jeremiah (Humans), Georgie Henley (The Chronicles of Narnia films), Alex Sharp (How to Talk to Girls at Parties) and Toby Regbo (Fantastic Beasts: The Crimes of Grindelwald), Jamie Campbell Bower (The Mortal Instruments: City of Bones) and Naomi Watts (Mulholland Drive) onscreen.

Based on the hugely-popular universe created by author George R.R. Martin, the show will be written by Kingsman: The Secret Service scribe Jane Goldman and will detail what went on thousands of years before the likes of Jon Snow, Daenerys Targaryen, Sansa Stark, Arya Stark and Cersei Lannister began battling it out for a place on the Iron Throne.

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According to the network, the series will is set to reveal “the horrifying secrets of Westeros’ history to the true origin of the White Walkers, the mysteries of the East to the Starks of legend.” Either way, “it’s not the story we think we know.”