Jotun (also spelled Jotunn, or Etin, "devourer"), in Norse mythology, the race of giants that was descended from the primordial being Ymir, the first frost giant, whose existence preceded that of Buri, the ancestor of the gods.
The first Aesir gods, the brothers Odin, Vili, and Ve, killed Ymir and used his body to create the world, setting aside different realms for humans, gods, giants, and dwarfs. For the giants, they created the realm of Jotunheim, also called Utgard. It was a vast, cold, mountainous, inhospitable land in which the surviving giants could live.
Most of the giants were evil, and they were the perpetual enemies of the gods. The god Thor, in particular, was famous for his escapades in Jotunheim and his penchant for giant-killing. Many Norse poems and tales center on conflicts between gods and giants, an animosity that it was thought would culminate in Ragnarok, the battle at the end of the world.
Judging from the surviving literature, the best-known group of Jotuns were the frost giants, collectively called the Hrimthursar, rough-hewn creatures with heads as hard as stone and with feet of ice. But other myths involved encounters with mountain giants, and there were also fire giants and sea giants. Some of these giants were capable of shape-shifting, assuming the form of animals such as wolves, eagles, or even dragons, and of creating illusions to confuse the gods.
Loki, the trickster fire god, was actually the son of giants, and Loki's monstrous children, the wolf Fenrir and the serpent Jormungand, were really giants in animal form. Other giants who figure prominently in Norse mythology are Thiassi, who stole the goddess Idunn, keeper of the apples of youth; Thrym, who stole Thor's magic hammer, Mjolnir, and bargained to exchange it for the goddess Freya; the magician Utgard-Loki (a name used by Skrymir, a king of the giants) who tricked Thor in a test of Thor's strength; and the unnamed mountain giant who contracted with the gods to build them the huge fortification of Asgard.
The harsh Scandinavian weather and terrain is reflected in the names of the giants, among them Kari (Tempest), Beli (Storm), Thrym (Frost), Thiassi (Ice), Johul (Glacier), Frosti (Cold), Snoer (Snow), and Orifta (Snowdrift). Utgard was first settled by a giant named Norfi or Narfi, who was the father of Nott (Night).
The distinction between the gods and giants was not always a clear one, and some of the giants were not enemies of the gods at all. Aegir was a sea giant, sometimes considered a god, who threw banquets for the gods in his golden sea palace. The Asynjur goddesses, including Gerd and Skadi (Winter), were actually giantesses. Thor had two sons, Magni (Strength) and Modi (Courage), by a giantess named Jarnsaxa (Ironstone). Even Odin's mother, Bestla, was a giantess, and the mysterious sage Mimir may have been her brother. Mimir, ruler of lakes and pools, though usually considered a giant was often consulted by Odin on account of his great wisdom, and he was so strongly identified with the Aesir gods that he represented them in a hostage exchange that was part of a peace pact they made with the Vanir gods.
Nevertheless, the hatred between gods and giants would ultimately lead to all-out war. At the time of Ragnarok, the giant Hrym would captain the frost giants' ship Naglfar. The fire giant Surt, guardian of the primordial fiery realm of Muspelheim, would lead an army of fire giants and set the world on fire, and the gods would perish in the very act of freeing the world of evil.