Nanook, from the Inuktitut nanuq, "polar bear", is the spirit lord and master of polar bears in Inuit tradition, understood as controlling the availability of bears to hunters much as Sedna controls the sea mammals, and requiring similarly careful, respectful treatment of a killed bear's body and remains to maintain his goodwill toward the hunter's community.
The polar bear itself held an unusually significant and dangerous place in traditional Inuit life, both a valuable source of meat, fur and material and one of the few animals genuinely capable of killing a human hunter in return, and this real, mutual danger is reflected in the seriousness with which traditional practice treated the ritual obligations owed to Nanook, including specific taboos governing how a bear's body could be handled, distributed and disposed of after a successful hunt. Some Inuit narrative traditions describe Nanook as himself resembling an enormous or otherwise supernatural bear, blurring the line between a spirit ruling over an animal species and the animal's own most powerful, semi-divine exemplar, a pattern also found in other circumpolar master-of-animals traditions.