Norse cosmology

In Norse mythology, and henceforth the Marvel Universe, there exist the Nine Worlds of Norse mythology, including Earth. These planets share a theoretical link in the branches of Yggdrasill.

Alfheim
Alfheim is the home of the Ljósálfar, or Light Elves, a peaceful race who avoid war on all accounts.

Asgard
Asgard is the home of the gods of Norse mythology. The most advanced and diplomatic of all races in the Nine Worlds, the Asgardians base their existence on a belief that death on the battlefield is the only way to gain access into Valhalla, the afterlife for the honoured dead. Asgard is the realm where the Bifrost bridge is based. Odin is king of Asgard.

Helheim
Helheim is the world of the dead who are neither honoured nor dishonoured. Their ruler is Hel, Loki's daughter.

Jotunheim
Jotunheim is the home of two races of jötunn, the Frost Giants and the Rock Giants. The jotunns are a savage culture ruled by senile giant Ymir, one of the oldest creatures in the universe.

Midgard
Midgard is the Asgardian word for Earth. Though the humans are mostly unaware of the other realms, Earth is joined with the Asgardian dimension.

Muspellheim
Muspellheim is realm to the fire Jotunn, also known as demons, ruled by Surtur, Odin's most feared enemy. The Ragnarok prophecies predict that the "Sons of Muspell" will signal the end of times by destroying Bifrost.

Niðavellir
Nidavellir is the realm of the dwarves. Their king is Hreiðmarr.

Svartalheim
Svartalheim is the home of the Dark Elves, a cousin race of the Light Elves who dabble in dark magic and obsession with conquering.

Vanaheim
Vanaheim is home to the Vanir, an angelic sister race of the Asgardians who are associated with wisdom and fertility.