Muspelheim, also called Muspel (from Old Norse Múspellsheimr and Múspell, respectively), is the realm of fire in Norse mythology. It is the home of the Fire Giants, of whom Surt was the ruler. Muspelheim means world of fire or home of fire, Muspel being fire and Heim, home or world.

Muspelheim is believed to have been the highest of all the realms, and was above Asgard, the home of the Aesir. Further south was Jötunheim, the realm of ice and the Jötnar.

In Norse mythology creation begins from the contact between fire and ice in the immense initial void known as Ginnungagap, creating the ether. The bright objects of the night sky, such as planets, comets and stars emerged from the sparks of Muspelheim.

In Ragnarök, the heavens will open and Surt will emerge from Muspelheim followed by all his giants, marching towards Asgard and destroying the Bifrost Bridge in his path.