Game of Thrones season four is welcoming a new cast member when it returns, and we're sure pop culture buffs will nerd out over this one: Sherlock co-creator and star Mark Gatiss has been cast on the HBO fantasy hit as...

We don't know! Yes, Gatiss' role is being kept top-secret, much like Iwan Rheon's role prior to season three. (He was later revealed to be Ramsey Bolton).

In addition to his time opposite Benedict Cumberbatch on BBC's beloved Sherlock as Holmes' brother Mycroft, Gatiss has written plays and Doctor Who novels and acted in three episodes of the cult classic TV series.

Sherlock, Doctor Who and Game of Thrones? That's like the geek Triple Crown! st reported Gatiss' casting.

滬江娛樂(lè)：《權(quán)力的游戲》第四季回歸時(shí)會(huì)迎來(lái)一個(gè)新角色，英劇《神探夏洛克》的劇作者兼演員馬克·加蒂斯（在《夏洛克》中飾演夏洛克的哥哥）將會(huì)出演HBO的史詩(shī)巨作《冰與火之歌：權(quán)力的游戲》第四季，至于出演什么角色，我們還不知道。據(jù)悉，《權(quán)力的游戲》第四季和《神探夏洛克》第三季都將于2014年播出。