Question: Hafþór Júlíus Björnsson plays an HBO character who first appears in book form in what year?

full_context: Document 1: Eddie Hall: Edward Hall (born 15 January 1988) is an English professional strongman, notable for being the current World's Strongest Man and the only man to deadlift 500 kg under strongman rules. He has also won on multiple occasions both the UK's Strongest Man and England's Strongest Man titles. He is the 2017 World's Strongest Man and the current world record holder in the deadlift with straps.
Document 2: Gregor Clegane: Gregor Clegane, nicknamed "The Mountain That Rides" or simply "The Mountain", is a fictional character in the "A Song of Ice and Fire" series of fantasy novels by American author George R. R. Martin, and its television adaptation "Game of Thrones". In the books, the character is initially introduced in 1996's "A Game of Thrones". He subsequently appeared in "A Clash of Kings" (1998), "A Storm of Swords" (2000) and in "A Dance with Dragons" (2011).
Document 3: Brienne of Tarth: Brienne of Tarth is a fictional character in George R. R. Martin's "A Song of Ice and Fire" series of fantasy novels. She is a prominent point of view character in the fourth novel, "A Feast for Crows", and a main character in the television adaptation. She is introduced in the second novel in the series, "A Clash of Kings".
Document 4: Hafþór Júlíus Björnsson: Hafþór Júlíus "Thor" Björnsson (] ; also Hafthor Julius Bjornsson, born November 26, 1988) is an Icelandic professional strongman, actor, and former professional basketball player. He plays Ser Gregor "The Mountain" Clegane in the HBO series "Game of Thrones".
Document 5: Bran Stark: Brandon Stark, typically called Bran, is a fictional character in the "A Song of Ice and Fire" series of fantasy novels by American author George R. R. Martin, and its television adaptation "Game of Thrones". Martin told "Rolling Stone" in 2014 that Bran's chapter with Jaime and Cersei Lannister is what "hooked" many readers early in the first novel.
Document 6: Gendry: Gendry is a fictional character in the "A Song of Ice and Fire" series of fantasy novels by American author George R. R. Martin, and its television adaptation. "Game of Thrones". He is a non-POV character, first appearing in 1996's "A Game of Thrones", and subsequently appeared in "A Clash of Kings" (1998), "A Storm of Swords" (2000) and "A Feast for Crows" (2005). Gendry is an apprentice blacksmith in King's Landing, and an unacknowledged bastard of King Robert Baratheon.
Document 7: Jaime Lannister: Jaime Lannister is a fictional character in the "A Song of Ice and Fire" series of fantasy novels by American author George R. R. Martin, and its television adaptation "Game of Thrones". He becomes a prominent point of view character in the novels beginning in "A Storm of Swords" (2000).
Document 8: Cersei Lannister: Cersei Lannister is a fictional character in the "A Song of Ice and Fire" series of fantasy novels by American author George R. R. Martin, and its television adaptation "Game of Thrones", where she is portrayed by Lena Headey. In the novels, she is a point of view character.
Document 9: Brian Shaw (strongman): Brian Shaw (born February 26, 1982) is an American professional strongman competitor and winner of the 2011, 2013, 2015 and the 2016 World's Strongest Man competitions. Shaw is also the first man to have won the Arnold Strongman Classic and the World’s Strongest Man contest in the same calendar year, a feat he accomplished in 2011 and then replicated in 2015.
Document 10: Eddie: Strongman: Eddie: Strongman is a 2015 British documentary film directed by Matt Bell. It follows the life of English strongman Eddie Hall as he strives to become the World's Strongest Man, which he later achieved in 2017. The film provides a unique insight into the extreme lifestyle of an international strongman and the sacrifices he must make to achieve his goals. It features appearances from Arnold Schwarzenegger, Brian Shaw, Žydrūnas Savickas, Hafþór Júlíus Björnsson, Benedikt Magnússon, Terry Hollands, and Geoff Capes.
Document 11: Tyrion Lannister: Tyrion Lannister (also referred to as "the Imp" or "the Halfman") is a fictional character in "A Song of Ice and Fire", a series of fantasy novels by American author George R. R. Martin and its television adaptation "Game of Thrones". Based on an idea that came to Martin while writing the 1981 novel "Windhaven", Tyrion has been called one of the author's finest creations and most popular characters by "The New York Times". Martin has named the character as his favorite in the series.
Document 12: 1986 World's Strongest Man: The 1986 World's Strongest Man was the tenth edition of World's Strongest Man and was won by Jón Páll Sigmarsson from Iceland. It was his second title after finishing second the previous year. 1983 and 1985 champion Geoff Capes from the United Kingdom finished second and, Ab Wolders from the Netherlands finished third. The contest was held at Nice, France.
Document 13: Rory McCann: Rory McCann (born 24 April 1969) is a Scottish actor and musician, best known for portraying Sandor Clegane on the HBO series "Game of Thrones" and Lurch in Edgar Wright's crime-comedy "Hot Fuzz".
Document 14: 2013 World's Strongest Man: The 2013 World's Strongest Man was the 36th edition of World's Strongest Man. The event was held in Haitang Bay, Sanya, China, the same host city as the 2006 World's Strongest Man contest. The qualifying heats were held from August 17–20 and the finals on Aug. 23 & 24. The event was sponsored by the Commerce Casino and will be broadcast in the United States on the CBS Sports Network. Brian Shaw from the United States placed first, winning his second WSM title after winning in 2011. Zydrunas Savickas from Lithuania was second after finishing 1st the year before, and Hafþór Júlíus Björnsson from Iceland was third for the second year in a row.
Document 15: High Sparrow: The High Sparrow is a fictional character in the "A Song of Ice and Fire" series of high fantasy novels by American author George R. R. Martin and its television adaptation "Game of Thrones". His real name is unknown. The High Sparrow first appears in "A Feast for Crows" (2005). He subsequently appeared in Martin's "A Dance with Dragons" (2011).
ground_truth: 1996