User blog comment:KillRoy231/Why'd they have to spare Gregor?/@comment-5014364-20150512031646/@comment-25358400-20150512103130

His skull is sent to Doran Martell in Dorne, as a token of justice for the deaths of Oberyn, Elia, and her children. The rest of Clegane's body is kept "alive" (or at least animate) by the dark arts/experiments of Qyburn. He is incased in a giant suit of armor, and reintroduced as "Ser Robert Strong".