Killua has blue eyes, a very pale complexion, and silvery-spiky hair. You can see different shapes of his eyes depending on how he’s feeling. Like when he’s in assassination mode, they become sharper and narrower. He had a lean figure, due to his early physical training. That training was under torture and continual physical conditioning. He likes to influence his attacks with lightning, and increase his speed with “Godspeed”, a form that makes him glow, and makes him move at, well, godspeed.