In Norse mythology there are a race of giant nature spirits with superhuman strength and abilities. One of these giants is known as a jötunn or jotun. These giants are described as being the opposing race to the two tribes of Æsir and Vanir. However, jotunn are known to intermarry with the other tribes. The homeland of the jotunn is Jotenheimr, which in Norse cosmology, is one of nine worlds seperate from the human world know as Midgard. Midgard is protected by giant mountains and dense forests. In more recent history, Scandanavian folklore takes the concept of the jotunn and simplifies the nature spirit notion to trolls.
Old Norse mythology refers to the giant spirit being as jotnar or jotunn, and both words became interchangeable as both singular and plural. The origin of the work jotunn has the same root as the word "eat" with an original meaning of a glutton or a mythological "man-eater."
The Norse Jotnar mythology story originates with Ginnungagap as a monumental giant that formed out of primeval chaos. As the giant slept, a jotunn son and daughter emerged from the pits of his arms. Ginnungagap's feet conceived and gave birth to a son, who was a monster with six heads. These three offspring are the creators of the race of "rime thurs" and populated Niflheim, which is the world of mist and ice.
These creatures, known to the ancient Norsemen as gods, claimed their origin came from a god named Buri, not Ginnungagap. After a giant named Tmir was slain by the three grandsons of Buri who were Odin, Vili and Ve; Ymir's blood flooded Niflheim killing all of the jotnar, except for one being named Bergelmir and his wife, who then repopulated their kind.
This story is similar to dozens of other ancient stories telling of a great flood that destroyed the world, such as Noah's flood from the Bible, and the Epic of Gilgamesh. Interestingly, both of these stories also claimed the lives of a race of evil giants known as the Nephilim, while saving a single family to repopulate the planet.
The characteristics of the jotnar are often described as hideous with claws, fangs, deformed body parts, and of course a gigantic size. One such giant or jotunn named Thrivaldi had nine heads and did not resemble a human being in shape. Jormungandr and Fenrir, the two children of Loki are known in the mythology to be hideously deformed as well.
Strangely when the jotnar were named by the ancient Norsemen, they were often described as having the very opposite characteristics as some of the earlier-named deformed jotnar. These newer jotnar were known to be wise men holding wisdom from bygone times. The gods Mimir and Odin were two giants who went on a journey to discover this lost ancient knowledge.
A large portion of the gods's spouses are minor-goddess giants. Njoror is married to a humanoid giant named Skaio, while Odin is married to a humanoid giant named Gunnlod. The much more well-known and most popular Norse god; the god of thunder, Thor, has two giant wives named Jarnsaxa and Magni. Within the mythlogy, they are believed to be lesser gods.
There is a final class of jotnar that exist called Muspellsmegir, which are fire jotnar. In Norse mythology, the main roles of the fire jotnar are to destroy the world by setting fire to the world at the end of Ragnarok, which is "the chosen time" when the jotnar and the forces of the god Hel will launch an attack on all the other gods, leaving only a small few of the gods left to rule the universe.