Question: Who was the author of the book series that the TV series is based on that Maisie Williams made her debut on?

Context paragraphs:
IBoy: iBoy is a British science-fiction teen thriller film on Netflix, starring Bill Milner and Maisie Williams.  It is based on the 2010 novel of the same name by Kevin Brooks.

Ann Sothern: Ann Sothern (born Harriette Arlene Lake; January 22, 1909 – March 15, 2001) was an American actress who worked on stage, radio, film, and television, in a career that spanned nearly six decades.  Sothern began her career in the late 1920s in bit parts in films.  In 1930, she made her Broadway stage debut and soon worked her way up to starring roles.  In 1939, MGM cast her as Maisie Ravier, a brash yet lovable Brooklyn showgirl.  The character, based on the "Maisie" short stories by Nell Martin, proved to be popular and spawned a successful film series ("Congo Maisie", "Gold Rush Maisie", "Up Goes Maisie", etc.) and a network radio series ("The Adventures of Maisie").

Rachel Williams (footballer): Rachel Louise Williams (born 10 January 1988) is an English international women's footballer.  Before joining Notts County, Williams spent one year at Chelsea Ladies and three years at Birmingham City Ladies, where she was converted from an attacking midfielder to a striker.  Williams made her senior England debut in July 2009 but had to wait two years for her next appearance, missing out on selection for Women's Euro 2009 and the 2011 Women's World Cup.  She was selected in the Great Britain squad for the 2012 London Olympics.

Arya Stark: Arya Stark is a fictional character in American author George R. R. Martin's award-winning "A Song of Ice and Fire" epic fantasy novel series.  She is a prominent point of view character in the novels, with the third most viewpoint chapters overall out of all the characters in the series so far, and is the only viewpoint character to appear in every published book of the series.

Ashildr: Ashildr (also known as Me) is a fictional character in the British science fiction television series "Doctor Who", portrayed by Maisie Williams, who was introduced in the ninth series episode "The Girl Who Died".

Gus Williams (outfielder): August Joseph "Gus" Williams, Jr. (May 7, 1888 – April 16, 1964), known also as "Gloomy" Gus Williams, was a German American professional baseball player whose career spanned 10 seasons, five of which were spent in Major League Baseball (MLB) with the St. Louis Browns (1911–15).  Over his major league career, Williams batted .263 with 171 runs scored, 367 hits, 58 doubles, 31 triples, 12 home runs, 147 runs batted in (RBIs), and 95 stolen bases in 410 games played.  Williams career started out in 1909 with the Monmouth Browns of the Class-D Illinois–Missouri League.  After playing in the minor leagues for two seasons, Williams made his major league debut in 1911.  He had another stint in the majors in 1912.  In 1913, Williams served as the Browns regular outfielder.  He was a dead-ball era power hitter for the Browns, ranking in the top-10 amongst American League hitters in home runs during the 1913 and 1914 seasons.  He led the league in strikeouts in 1914.  Williams would make his last appearance in the major leagues during the 1915 season.  He would go on to play in the minors with the Toronto Maple Leafs (1915), Nashville Volunteers (1916), Louisville Colonels (1917), and Indianapolis Indians (1918).  In the minors, he compiled a career batting average of .293 with 838 hits in 759 games played.  Williams also played semi-professional baseball after leaving the professional circuit.  He batted and threw left-handed.  During his baseball career, Williams stood at 6 ft and weighed 185 lb .

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.

The Book of Love (film): The Book of Love (originally titled "The Devil and the Deep Blue Sea") is an American drama film directed and rewritten by Bill Purple from an original script by Robbie Pickering featuring Maisie Williams, Jessica Biel, Jason Sudeikis, Mary Steenburgen, Orlando Jones, and Paul Reiser.

New Mutants (film): New Mutants is an upcoming American superhero film based on the Marvel Comics superhero team of the same name, distributed by 20th Century Fox.  It is intended to be the eleventh installment in the "X-Men" film series.  The film is being directed by Josh Boone from a screenplay by himself and Knate Lee, and stars Anya Taylor-Joy, Maisie Williams, Charlie Heaton, Henry Zaga, Blu Hunt, and Alice Braga.  In "New Mutants", a group of young mutants held in a secret facility fight to save themselves.

Marley Williams: Marley Williams (born 22 July 1993) is a professional Australian rules footballer playing for the North Melbourne Football Club in the Australian Football League (AFL).  He previously played for the Collingwood Football Club from 2012 to 2016.  He was recruited by Collingwood in the 2012 Rookie Draft, with pick #35.  Williams made his debut in Round 9, 2012, against Adelaide at Football Park.

Supporting paragraphs: Maisie Williams Arya Stark
Answer: George R. R. Martin