The Murder of Shae (Episode 10: 'The Children')
Yes, Tyrion Lannister kills his all-powerful father Tywin mere minutes later. (Meanwhile, earlier in the episode, Brienne of Tarth and Sandor "The Hound" Clegane pour a lifetime as outcasts into one final throwdown, and only one is left standing.) But the most emotionally resonant act of violence in the Season Four finale was also the most intimate, and the ugliest. Creeping into his former quarters in the Tower of the Hand, Tyrion discovers his estranged ex-girlfriend/key trial witness Shae has taken up with his hated father. There's a flash of recognition. There's a struggle. Then Tyrion strangles the woman he once loved to death. "I'm sorry," he says afterwards, crying. Sorry for whom or what? In the face of that act, hew knows the answers don't matter. Having previously partially redeemed some of its biggest villains, Game of Thrones has now damned one of its most beloved heroes. That's a move as bold as any Red Wedding or Ned beheading.