Game of Thrones already has one of the largest casts on TV, and now it’s getting even bigger. Entertainment Weekly reports that Mark Gatiss, who Americans may know as Mycroft Holmes from BBC's Sherlock, will be heading to Westeros (or Essos) in Season 4 of HBO’s fantasy epic.

Along with starring in Sherlock, Gatiss is the co-creator of the popular British detective series, and he also has a history with legendary British sci-fi series Dr. Who. Gatiss has written and appeared in several episodes of the classic time travel series. We wonder if he’ll be bringing his behind the scenes skills with him to GoT, too.

Gatiss is the second major new addition to the Season 4 cast, following Graceland’s Pedro Pascal, who will be portraying Oberyn Martell, AKA the Red Viper.

As far as who Gatiss will be portraying... we’re not sure yet. We do know that there are at least two confirmed roles that need to be filled for next season, those of Mace Tyrell and Styr, Magnar of Thenn. Could Gatiss step into one of these roles? Or could he be playing another, as-yet-unannounced character? We’ll just have to wait and see, but we’re totally excited about the possibilities!

Who do you think Mark Gatiss will play? Share your theories in the comments below!

Get more Game of Thrones spoilers here.

Source: Entertainment Weekly