In the Poetic Edda poem Vafþrúðnismál, the giant who competes with Odin in a contest of wisdom is Vafþrúðnir.
Odin visits the giant disguised as a traveler named Gagnráðr and challenges him to answer questions about the cosmos, the gods, creation, and the future. Vafþrúðnir is renowned for his knowledge and initially appears confident that he can defeat the stranger. The contest gradually moves from questions about the known world to secrets that only Odin could know.
Odin finally asks what Odin whispered into the ear of the dead god Baldr. Vafþrúðnir cannot answer, because the question reveals that his opponent is Odin himself. The giant therefore loses the wager, and the poem ends with Odin’s identity exposed.
Vafþrúðnismál means something like “The Sayings of Vafþrúðnir.” It is one of the Poetic Edda’s major wisdom poems and is especially valuable for its account of Norse creation and the events expected at Ragnarök.