Múspellsheimr (the Realm of Fire) is one of the two worlds that existed before the beginning of times, along with Nivlheim. It is the first in the spectrum of the nine worlds in Norse Mythology and borders to Alfheim.
Múspellsheimr is ruled by destructive forces of fire and heat. The creatures inhabiting this fiery realm are called Muspellsons, and are ruled by the powerful fire jötunn known as Surtr.
In colliding with the icy forces of Nivlheim, Múspellsheimr gave birth to the origins of all life, and in time it will also come to destroy all that it has once created.
In spite of it's central role in old norse mythology, very little else is known about this fiery world.