Which god is killed by the wolf Fenrir?

The wolf Fenrir kills Odin during Ragnarök.

Fenrir is a monstrous wolf and a child of Loki and the jötunn Angrboða. The gods fear him because prophecies foretell that he will become a great danger. They eventually bind him with Gleipnir, a magical fetter made from impossible ingredients, but Fenrir breaks free when Ragnarök begins.

At the final battle, Odin rides out against Fenrir while Thor is occupied fighting Jörmungandr, the Midgard Serpent. Fenrir swallows Odin, fulfilling the prophecy recorded in the Poetic Edda and Prose Edda. Odin’s son Víðarr immediately avenges him: in Snorri’s account, Víðarr forces open the wolf’s jaws and kills him.

Týr is commonly confused with Odin because Fenrir bites off Týr’s hand during the wolf’s earlier binding. Freyr, meanwhile, is killed by Surtr, and Thor dies from Jörmungandr’s venom after defeating the serpent. Thus Odin is the single canonical answer for Fenrir’s victim at Ragnarök.