The mountain range of southern Norway is likewise called in Norwegian Jotunheimen or the Jotunheim Mountains.
The first living being formed in the primeval chaos known as Ginnungagap was a giant of monumental size, called Ymir. When he slept a jötunn son and a jötunn daughter grew from his armpits, and his two feet procreated and gave birth to a son, a monster with six heads. These three beings gave rise to the race of hrímþursar (rime thurs), who populated Niflheim, the world of mist, chill and ice. The gods instead claim their origin from a certain Búri. When the giant Ymir subsequently was slain by Odin, Vili and Vé (the grandsons of Búri), his blood (i.e. water) deluged Niflheim and killed all of the jötnar, apart from one known as Bergelmir and his spouse, who then repopulated their kind.
Some of the jötnar are attributed with hideous appearances – claws, fangs, and deformed features, apart from a generally hideous size. Some of them may even have many heads, such as Thrivaldi who had nine of them, or an overall non-humanoid shape; so were Jörmungandr and Fenrir, two of the children of Loki.
Yet when jötnar are named and more closely described, they are often given the opposite characteristics. Very old, they carry wisdom from bygone times. It is the jötnar Mímir and Vafþrúðnir Odin seeks out to gain this ancient knowledge. Many of the gods' spouses are giants. Njörðr is married to Skaði, Gerðr becomes the consort of Freyr, Odin gains the love of Gunnlod, and even Thor, the great slayer of their kind, produces a child with Járnsaxa; Magni. As such, they appear as minor gods themselves, which can also be said about the sea giant Ægir, far more connected to the gods than to the other jötnar occupying Jotunheim. None of these fear light, and in comfort their homes do not differ greatly from those of the gods.
A certain class of jötnar are the fire jötnar (Múspellsmegir or eldjötnar), said to reside in Muspelheim, the world of heat and fire, ruled by the fire jötunn Surtr ("the black one"). The main role of the fire jötnar in Norse mythology is to wreak the final destruction of the world by setting fire to the world at the end of Ragnarök, when the jötnar of Jotunheim and the forces of Hel shall launch an attack on the gods, and kill all but a few of them.