( CNN ) -- British actors David Bradley and Mark Gatiss arrived at the party of film `` The World 's End '' together last night at Comic-Con to discuss their upcoming BBC film `` An Adventure In Space and Time . '' But the pair also have another project in common now . Bradley , who plays Walder Frey on `` Game of Thrones , '' can now cite Gatiss as one of his fellow cast members on the show . Gatiss was recently announced to be joining the hit HBO series , but his role remains something of a surprise . `` I 'm not allowed to tell you , '' Gatiss said . `` I 've done my filming . I 'm glad I did n't tell anyone before this since it 's a big secret . The announcement of ( my casting ) was obviously timed for Comic-Con and I 'm rather overwhelmed with the reaction , honestly . It 's a great show with so many brilliant people in it . '' Gatiss ' time on set was short , but that does n't necessarily indicate anything about the size of his role . `` What 's interesting is that it 's such a huge , sprawling cast and people seem to be there for ages , but they actually shoot two or three days and that 's it , '' he said . `` Once it 's put together it looks like everybody must be there for weeks and weeks and weeks . '' For Bradley , the past season of `` Game of Thrones '' was the most exciting for him . His character 's central role in the infamous `` Red Wedding '' scene depicted in the penultimate episode `` The Rains of Castamere , '' and has drawn an intense fan reaction due to the bloody death of several characters . But Bradley relates more his own character than those the fans have connected with . `` I felt intense pleasure ( killing them ) , which was alarming , '' Bradley said of watching the episode . `` I 'd do it all again if I had the chance . They got what was going to them ! '' Share your mini-interviews from Comic-Con . Bradley , who said he has n't read George R.R . Martin 's books that the show is based on , is filming the upcoming episodes , but he 's uncertain of Walder Frey 's fate beyond that . `` I do n't know what the future is on 'Game of Thrones , ' `` Bradley said . `` I was on Season 1 and I 'm just finishing Season 3 and I 'm moving on to Season 4 now , but whether I 'll be thereabouts ( going forward ) I just do n't know . It would be nice , but I just do n't know yet . '' Gatiss , best known for his role of Mycroft Holmes on BBC 's `` Sherlock '' ( he is also one of the creators ) , noted that he 's prepared for the fan obsession that accompanies being on a TV show like `` Game of Thrones . '' `` My life is entirely composed of fan obsession -- so this is just another one to add to it , '' Gatiss said . `` It 's all a Venn diagram . ''
`` Sherlock '' actor Mark Gatiss enjoyed his murderous role in the Red Wedding . `` Sherlock '' actor David Bradley just announced as new Thrones cast member . Gatiss is not allowed to reveal anything about his character .