Easily, easily Gaara. He grew up with eeeeveryone despising him for, to him, no reason. Like Naruto. The difference is, Gaara would accidentally brutally slaughter children when he'd try to play with them. The equivalent of Iruka in his life was Yashimaru, I think his name was. He was the only person who cared for Gaara. Gaara's own father, his own father, sent assassins to kill Gaara more than once. And the final time? Who was sent? Yashimaru. His final words to Gaara, "I hate you, Gaara. I always have."
Gaara was the definition of tormented and traumatized. He spiraled out of what little control he had when Yashimaru tried to murder him and became sociopathic, psychotic serial killer who spoke to his dead mother.
Gaara is the most traumatized character by far.
