A frequent contributor to British television is set to make his mark on HBO’s Game of Thrones.

Mark Gatiss, co-creator and actor on Sherlock and occasional Doctor Who writer and performer, has been cast on the fourth season of the popular HBO series.

Entertainment Weekly was the first to report the news, though there has been no word yet on which of the series’ many characters Gatiss will portray. Some have speculated that he will fill the role of Mace Tyrell, father to Loras (Finn Jones) and Margaery (Natalie Dormer).

Gatiss will be present at San Diego Comic-Con’s first ever Sherlock panel this weekend. It has not been revealed whether he will make an appearance at the Game of Thrones panel the next day, however.

Gatiss’ work can next be seen in the upcoming documentary An Adventure in Space and Time. The program, written by Gatiss, was created to celebrate the 50th anniversary of Doctor Who.