Mark Gatiss cast in Game of Thrones season 4

With filming now underway on the fourth season of Game of Thrones, showrunners David Benioff and D.B Weiss continue to add to the enormous cast of the epic fantasy series, with Entertainment Weekly revealing that the British actor, writer and producer Mark Gatiss has signed on to the HBO show for an as-yet-unrevealed role.

One of the co-creators of the cult comedy series The League of Gentlemen, Gatiss' subsequent credits including writing for (and guesting in) Doctor Who, as well as co-creating the BBC drama Sherlock, where he portrays Benedict Cumberbatch's on-screen brother Mycroft. He has also recently written the Doctor Who 50th anniversary docudrama An Adventure in Space and Time.

Unlike previous seasons, it seems like newcomers to the HBO show will be kept to a minimum this time around; aside from Gatiss, the only other actor confirmed as joining the cast is Pedro Pascal (Graceland), who will portray Oberyn Martell, a.k.a. The Red Viper.