Gregor Clegane


 * Sociopathic/Psychotic/Sadistic: Gregor Clegane has savagely murdered and raped hundreds of innocent, defenseless people for sheer amusement, including infants.
 * Spiteful: So petty and malicious that he stupidly admitted his worst war crime in public just to insult Oberyn Martell seconds before killing him.
 * Angry: Clegane is a savage locked in a state of hatred and sadism, extremely easy to set off. He even kills his horse because he lost a single joust.
 * Stupid: Rather than a typical sociopath who disregards human decency for pragmatic reasons, the Mountain is simply too stupid and thick-headed to remotely comprehend morality, and as mentioned above, places petty evil above anything resembling reason or pragmatism.