A Jötunn is a giant, a descendant of the first giant, Ymir, from whom the earth was made. Some of the jötnar are attributed hideous appearances such as claws, fangs, and deformed features, apart from a generally monstrous size. Some of them may even have many heads, such as Þrívaldi the Nine-Headed.
Yet when other jötnar are named and more closely described, they are often given the opposite characteristics. Many of the jötnar are described as beautiful, Skaði being described as the “bright bride of the gods". Although some jötnar are said to have been of considerable size, many were of no difference in size than that of the Æsir or Vanir.
Although many giants dwell in Midgard, they are native to the worlds of Jötunheim, Múspellsheim, and Niflheim. Jötunheim is the realm of the main lineage of giants: leirjötnar, bergrisar, sjórisar, and vindþursar. Eldjötnar, the fire giants, come from Múspellsheim, while hrímþursar hail from Niflheim. Trolls, ettins, hags, and other monstrous creatures are from a decayed branch of the family, found almost exclusively in Midgard.
The most famous giants in the lore are are Ymir, Hrungnir, Surtr, Thyrm, Mimir, and Skaði. In Vinland, jötnar dwell mainly in the north and west. Grýla and her children the Jólasveinar are infamous trolls who dwell in the black lava fields of Dimmuborgir, north of Ullarakr.