Question: Who is the writer of the series of fantasy novels of which the television series in which Ralph Ineson plays Dagmer Cleftjaw is an adaptation?
Context: Lisa Mantchev is an American author of fantasy novels and short stories.  She is best known for her Théâtre Illuminata series, a trilogy of young adult fantasy novels. Lloyd Chudley Alexander (January 30, 1924 – May 17, 2007) was an American author of more than forty books, primarily fantasy novels for children and young adults.  His most famous work is "The Chronicles of Prydain", a series of five high fantasy novels whose conclusion, "The High King", was awarded the 1969 Newbery Medal for excellence in American children's literature.  He won U.S. National Book Awards in 1971 and 1982. Ralph Michael Ineson (born December 15, 1969) is an English actor, best known as Dagmer Cleftjaw in "Game of Thrones", Amycus Carrow in the last three "Harry Potter" films, William in "The Witch" and Chris Finch in the BBC series "The Office". Red Data Girl (RDG レッドデータガール , Ārudījī Reddo Dēta Gāru ) is a series of fantasy novels written by Noriko Ogiwara.  Six volumes have been released.  The first volume was published by Kadokawa Shoten in 2008, while the last was published in 2012.  This manga series adaptation, illustrated by Ranmaru Kotone and published by Kadokawa Shoten, was serialized between December 2012 and July 2014.  A 12-episode anime television series adaptation by P.A.Works aired between April and June 2013.  The full anime series became available for streaming on Netflix (US) on August 1, 2015. Caroline Stevermer (born 1955) is a writer of young adult fantasy novels and shorter works.  She is best known for historical fantasy novels. The Shannara Chronicles is an American fantasy drama television series created by Alfred Gough and Miles Millar.  It is an adaptation of the "Shannara" series of fantasy novels by Terry Brooks, primarily "The Elfstones of Shannara". Justin Richards (born 14 September 1961) is a British writer.  He has written science fiction and fantasy novels, including series set in Victorian or early-20th-century London, and also adventure stories set in the present day.  He has written many spin-off novels, reference books and audio plays based on the long-running BBC science fiction television series "Doctor Who", and he is Creative Consultant for the BBC Books range of "Doctor Who" novels. Game of Thrones is an American fantasy drama television series created by David Benioff and D. B. Weiss.  It is an adaptation of "A Song of Ice and Fire", George R. R. Martin's series of fantasy novels, the first of which is "A Game of Thrones".  It is filmed in Belfast and elsewhere in the United Kingdom, Canada, Croatia, Iceland, Malta, Morocco, Spain, and the United States.  The series premiered on HBO in the United States on April 17, 2011, and its seventh season ended on August 27, 2017.  The series will conclude with its eighth season in 2018 or 2019. Katherine Irene Kurtz is an American fantasy writer, known for her sixteen historical fantasy novels in the "Deryni" series.  She also wrote several occult alternate history novels in her "Templar" series, and urban fantasy novels in her "Adept" series. Commando VIP is a British reality television show that aired on Five from 19 October to 23 November 2005.  It put six celebrities through tough military-style challenges after being trained by three real commandos.  The show was narrated by Ralph Ineson.
Answer: George R. R. Martin