“Game of Thrones” was bonkers from the start: Two dudes get their heads cut off in the opening minutes of the very first episode, and the madness doesn’t let up from there. Premiering in 2011 and running over eight seasons, the acclaimed HBO series draws on a series of fantasy novels from George R. R. Martin to tell the tale of a feudal kingdom beset by warring families, fire-breathing dragons, and all manner of supernatural forces.