Game Of Thrones: Arya’s Kill List - Where Are They Now?
8. The Mountain
Status: Alive... ish.
Though the Knight of the King's Guard was exceptionally dishonourable and notoriously cruel, Ser Gregor Clegane gained lands, titles and loads of money for his critical role in Robert's Rebellion at the Sack of King's Landing. That's not to say becoming a knight stopped the Mountain's savagery and thirst for blood, though.
It appears as though The Mountain was born deranged. When young Sandor touched his toys, the elder Clegane brother pushed his face into the fire.
Confined at Harrenhal, Arya saw his cruelty first hand when he hand-picked random villagers to be tortured by his trusty sociopath and right-hand man, "The Tickler."
It's unclear whether or not the dead - yet very much alive - Ser Gregor Clegane remains on the kill list given his current state of Franken-Knight, but no doubt Arya Stark hasn't forgotten.