question: Gregor Clegane appeared in what novel that  is the fifth novel in the series, "A song of Ice and Fire".
answer: A Dance with Dragons
context: Title: Ascending
  Passage: Ascending is a science fiction novel by the Canadian writer James Alan Gardner, published in 2001 by HarperCollins Publishers under its various imprints.  It is the fifth novel in Gardner's "League of Peoples" series.  It is a direct sequel to the first novel in the series, "Expendable", in that it picks up the dual story of Festina Ramos, Explorer turned admiral, and the transparent glass woman Oar, where the earlier novel left off.
  Title: Persistence of Memory
  Passage: Persistence of Memory is the tenth novel by American teen author Amelia Atwater-Rhodes and is the fifth novel in her Den of Shadows series.  Published on December 9, 2008 the novel tells the story of Erin Misrahe and her struggles with her alter-ego Shevaun, who is in fact a vampire with whom Erin has a link.  The novel also mentions a character from Atwater-Rhodes's previous novel, "In the Forests of the Night" (1999), Alexander, the brother of the protagonist, Risika.  The poem by Edgar Allan Poe entitled "A Dream Within a Dream" is featured in the novel.
  Title: The Dark Tower V: Wolves of the Calla
  Passage: Wolves of the Calla is the fifth novel in Stephen King's "The Dark Tower" series.  This book continues the story of Roland Deschain, Eddie Dean, Susannah Dean, Jake Chambers, and Oy as they make their way toward the Dark Tower.  The subtitle of this novel is "Resistance".  Prior to the novel's publication, two excerpts were published: "Calla Bryn Sturgis" was published in 2001 on Stephen King's official site, and "The Tale of Gray Dick" was published in 2003 in "McSweeney's Mammoth Treasury of Thrilling Tales".  Both excerpts were incorporated in revised form into the novel.  "Wolves of the Calla" was nominated for the Locus Award for Best Fantasy Novel in 2004.
  Title: A Dance with Dragons
  Passage: A Dance with Dragons is the fifth of seven planned novels in the epic fantasy series "A Song of Ice and Fire" by American author George R. R. Martin.  In some areas the paperback edition was published in two parts titled "Dreams and Dust" and "After the Feast".  It was the first novel in the series to be published following the commencement of the HBO series adaptation, "Game of Thrones", and runs to 1,040 pages.
  Title: Gregor Clegane
  Passage: 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).
citations: A Dance with Dragons Gregor Clegane