In Norse mythology, Muspelheim (Old Norse: Múspellsheimr), also called Muspell (Old Norse: Múspell), is a realm of fire. This realm is one of the Nine Worlds and it is home to the fire jötunn or the "sons of Muspell", and Surtr, their ruler. It is fire; and the land to the North, Niflheim, is ice. The two mixed and created water from the melting ice in Ginnungagap.
According to the Ragnarök prophecies in Snorri Sturluson's Gylfaginning, the first part of his Prose Edda, the sons of Muspell will break the Bifröst bridge, signaling the end of times:
In the midst of this clash and din the heavens are rent in twain, and the sons of Muspell come riding through the opening. Surtr rides first, and before him and after him flames burning fire. He has a very good sword, which shines brighter than the sun. As they ride over Bifrost it breaks to pieces, as has before been stated. The sons of Muspel direct their course to the plain which is called Vigrid.... The sons of Muspel have there effulgent bands alone by themselves.
The etymology of "Muspelheim" is uncertain, but may come from Mund-spilli, "world-destroyers," "wreck of the world."
In popular culture 
The realm of Muspelheim appears as 'Muspel' in Gene Wolfe's book series, The Wizard Knight. It is inhabited by the dragon 'Setr', as a close parallel to Surtr.
Muspelheim is the name of a reoccurring boss ship in the Naval Ops: Warship Gunner series.
See also