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  ===Casting===
  Actor Rory McCann returned as a series regular in his role as Sandor "the Hound" Clegane, last appearing in the season four finale.
  The episode featured the return of several characters from previous seasons, as well as the introduction of new characters, who were either mentioned previously within the show, or had some connection to an established character. Rory McCann, who portrayed Sandor "the Hound" Clegane from the beginning of the series through the fourth-season finale episode "The Children", returned as a series regular. McCann had previously speculated about the return of the Hound, saying in an interview with ''Access Hollywood'' in 2014, "There's always hope." Bryan Cogman revealed in an interview with ''Entertainment Weekly'' that there was always a plan to bring back the Hound, but the manner in which he was reintroduced was not always entirely known.
  Another re-introduction involved the storyline surrounding the Siege of Riverrun, with actor Clive Russell returning to the show as Brynden "the Blackfish" Tully, who last appeared in the third-season episode "The Rains of Castamere", in which the Red Wedding took place, and the Blackfish successfully evaded. In an interview with IGN, Clive Russell stated he was hopeful to return to the role saying "I'd hoped that he'd come back because he comes back in the books again. But they're not doing the books -- there is no book to do it from. I'd hoped that would happen. I don't think I was surprised it would happen because they bring back all kinds of people at all kinds of times. But it was good to go back there, I must say."
  Ian McShane, who previously starred in the HBO television series ''Deadwood'', guest starred in the episode as Ray. His casting for the series was announced in August 2015. At the time, McShane described his role in the show as the leader of a peace cult, who was also a former warrior that has since renounced violence, also noting that it was a "complete one-off." McShane also revealed that his character would "bring back a much-loved character everybody thinks is dead," leading many to speculate prior to the season that he would either play a role in bringing back Jon Snow, or the Hound, whose fate had also been called into question since his disappearance. McShane was asked about whether there was pressure involved with joining a show that has become an "international hit," with McShane responding "No pressure! It's the most popular TV show in the world, isn't it? I enjoyed meeting showrunners David Benioff and Dan Weiss – nobody ever expects the kind of reaction this has gotten. It's kind of like ''Deadwood'' when we started off, but they've managed to go another three seasons. It's interesting because you're a part of the show, but you're not part of the show. I only needed Rory for my scenes, so I didn't meet anybody else in it." Bryan Cogman stated that the character of Ray was a combination of several different characters from the ''A Song of Ice and Fire'' series, most evidently the Elder Brother, and Septon Meribald.
  With Jon Snow, Sansa Stark, and Davos Seaworth's attempt to unite the North against the Boltons, two different House leaders were cast to portray Lyanna Mormont and Robett Glover, with Bella Ramsey and Tim McInnerny portraying each character, respectively. Cogman noted about Bella Ramsey, "Bella is a terrific young actress – the whole cast and crew were very impressed. I think, much like the character does with Jon, Sansa, and Davos, Bella kept Kit, Sophie, and Liam on their toes!"
  Jerome Flynn, who portrays Bronn in the series, made his first appearance in the season, last appearing in the season five finale episode "Mother's Mercy".