From an interview of Gemma Arterton...and Ian Beattie

BOXSET
Game of Thrones is completely addictive, even if the acting isn’t great. My favourite character was Charles Dance’s Tywin Lannister, who was so evil but so compelling. Spoiler alert: he’s not my favourite actor in it any more. What a way to go…

http://www.standard.co.uk/lifestyle/london-life/gemma-arterton

actor Ian Beattie, who portrays Meryn(GoT)

When you were on set, was it hard not being spoiled by other actors?

- I was filming a scene with Nikolaj Coster-Waldau last year, and as soon as I had finished, I walked off, and there was Charles Dance. He turned around and he said, "Well, the little bastard finally killed me!" Which basically just gave away the whole end of the season for me. And I had managed to avoid finding out the whole time, until he told me! I'd like to have as good of a surprise as everyone else. [Laughs.]

http://www.vulture.com/2015/06/game-of-thrones-ian-beattie-on-that-horrific-death-scene.html