Killua is a very strong boy, he protects and cares about his loved ones. Killua has spiky silver hair, very pale skin and blue eyes. His eyes change shape depending on the mood that he's in, narrowing and sharpening when he goes into assassin mode. Killua is fairly lean at the start of the series, due to constant physical conditioning and torture training he received when he was young, but he's the most strongest Zoldyck now.