Question: What character is initially introduced in 1996's "A Game of Thrones is played by Hafþór Júlíus "Thor" Björnsson ?
Sentence (from "Gregor Clegane"): He subsequently appeared in "A Clash of Kings" (1998), "A Storm of Swords" (2000) and in "A Dance with Dragons" (2011).
Relevant evidence: No