Vafþrúðnir is a wise jötunn in Norse mythology. His name comes from Vaf, which means weave or entangle, and thrudnir, which means strong or mighty. Some interpret it to mean "mighty in riddles". It may be anglicized Vafthruthnir or Vafthrudnir. In the Poetic Edda poem Vafþrúðnismál, Vafþrúðnir acts as Odin's host and opponent in a deadly battle of wits that results in Vafþrúðnir's defeat.

A jötunn is a type of being in Germanic mythology. In Norse mythology, they are often contrasted with gods and other non-human figures, such as dwarfs and elves, although the groupings are not always mutually exclusive. The entities included in jötunn are referred to by several other terms, including risi, þurs and troll if male and gýgr or tröllkona if female. The jötnar typically dwell across boundaries from the gods and humans in lands such as Jötunheimr.