2. Arya Stark
Post-Traumatic Stress Disorder
Arya Stark is a child of war. Many of her family members are dead, she personally witnessed her father's execution, and saw the rest hounded and persecuted whilst being hounded and persecuted herself - all by the age of 11.
Following this trauma Arya exhibits many of the symptoms associated with PTSD. She has regular outbursts of anger and sometimes finds it difficult to control her aggression and emotions. She has difficulty falling asleep (at least until reciting her death list, but who doesn't, right?), she has intrusive thoughts and dreams and maintains a hyper-vigilance to danger.
Her obsessive "death list" is also an indicator of associated OCD type behaviour, which can be associated with PTSD. Her co-dependent relationship with The Hound, who also displays symptoms of PTSD, could work as a mutual defence mechanism against their triggers.
Let's not even get into the Dissociative identity disorder thing in her latest storyline with The Faceless Men.