Karaku was an Av-matoran who lived in Karda nui. Often mistaken as a shadow matoran due to the way he rebuilt himself, he escaped Karda nui during the 2008 saga and now lives on Metru nui.
He declined being returned to the light, as his current state makes him better at his job: Archiving different artifacts under the direction of turaga Whenua.
He often uses his wings to cover his body, as a sort of cloak...