Question: What author wrote the book series on which an HBO fantasy television series Joseph Jason Namakaeha Momoa starred on was based?

Context paragraphs:
Sophie Turner: Sophie Turner (born 21 February 1996) is an English actress.  Turner made her professional acting debut as Sansa Stark on the HBO fantasy television series "Game of Thrones" (2011–present), which brought her international recognition.

Jason Momoa: Joseph Jason Namakaeha Momoa (born August 1, 1979) is an American actor, model, director, writer, and producer.  He is known for his television roles as Ronon Dex on the military science fiction television series "Stargate Atlantis" (2004–2009) and as Khal Drogo in the HBO fantasy television series "Game of Thrones" (2011–2012).

List of Carnivàle episodes: "Carnivàle" is an American fantasy television series created by Daniel Knauf for HBO.  The series premiered on September 14, 2003, on HBO and finished its two-season run of 24 episodes on March 27, 2005.  Until late in the second season, each episode is split into two distinct but slowly converging storylines taking place in the United States Dustbowl of the mid-1930s.  Nick Stahl starred as Ben Hawkins, a young Okie farmer with strange powers who joins a traveling carnival; Clancy Brown played his adversary Brother Justin Crowe, a California preacher who uses his similarly strange abilities to rise to power.  "Carnivàle" was originally intended to run as a trilogy of paired seasons, with each pair being called a "book" and the series as a whole spanning the years from 1934 to 1945, but the series was canceled after two seasons due to low ratings.  These two seasons complete the first book covering the years 1934 and 1935.  The second book (seasons three and four) would have taken place around the years 1939 and 1940, and the third book (seasons five and six) would have played in 1944 and 1945, leading up to the end of World War II and the explosion at the Trinity test site.

Encantadia (2016 TV series): Encantadia is a Philippine fantasy television series by GMA Network based from the 2005 fantasy television series of the same name.  Acting as a reboot (often called as "requel" or retelling-sequel), it was the fourth series in the Encantadia franchise and was aired eleven years after the third one.  The show premiered on July 18, 2016 in the Philippines and worldwide through GMA Pinoy TV and ended on May 19, 2017.  It is also shown exclusively online through iflix at 1080p high-definition video as video on demand.

Maisie Williams: Margaret Constance "Maisie" Williams (born 15 April 1997) is an English actress.  She made her professional acting debut as Arya Stark in the HBO fantasy television series "Game of Thrones" in 2011, for which she won the EWwy Award for Best Supporting Actress in a Drama, the Portal Award for Best Supporting Actress – Television and Best Young Actor, and the Saturn Award for Best Performance by a Younger Actor.  In 2016, she was nominated for a Primetime Emmy Award for Outstanding Supporting Actress in a Drama Series.

Freddie Stroma: Frederic Wilhelm C.J. Sjöström (born 8 January 1987 ), known professionally as Freddie Stroma, is an English actor and model of Swedish and German descent, best known for playing Cormac McLaggen in the "Harry Potter" film series and Luke in the 2011 musical comedy film "".  He starred as Adam Cromwell on the dramedy series "Unreal", which premiered on Lifetime in June 2015.  He starred as Brit Vayner in the 2016 Michael Bay war film, "".  In 2016, he played Dickon Tarly in the sixth season of the HBO fantasy drama series "Game of Thrones" and H.G. Wells in the ABC series, "Time After Time".

Bella Ramsey: Bella Ramsey (born 2004) is an English actress.  She made her professional acting debut as the young noblewoman Lyanna Mormont in the HBO fantasy television series "Game of Thrones".

Game of Thrones title sequence: The title sequence of the HBO fantasy television series "Game of Thrones" introduces every episode and changes depending on the locations visited in that particular episode.  The title sequence was created by Elastic for HBO, and is accompanied by a theme tune composed by Ramin Djawadi.

Valar Dohaeris: "Valar Dohaeris" is the third season premiere of the HBO fantasy television series "Game of Thrones", and the 21st episode of the series.  Written by executive producers David Benioff and D. B. Weiss, and directed by Daniel Minahan, it aired on March 31, 2013.

Khal Drogo: Khal Drogo 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".

Supporting paragraphs: Jason Momoa Khal Drogo
Answer: George R. R. Martin