The Nine Worlds of Asgardian cosmology are the separate worlds of that dimension supported by Yggdrasill, the World Tree. Although the realms are commonly divided into nine, further subdivisions can be made (i.e. Valhalla is a distinct portion of Asgard). Additionally, a tenth realm called Heven was previously cut-off from the rest of Yggdrasill until the death of the Watcher revealed its existence. Thanks to the Allspeak, all Asgardians and related races can communicate in all of the languages of the Nine Realms, Earth's dialects, and various alien languages.
- Alfheim (Ljosalfheim): Home of the Light Elves.
- Asgard: Home of the Aesir, later forming the Asgardians with the Vanir.
- Vanaheim: Home of the Vanir, the sister race of the Asgardians.
- Jotunheim: Home of the Jötunn (Frost Giants).
- Midgard (Earth): Home of the Humans.
- Nidavellir ("The Dark Fields"): Home of the Dwarves.
- Svartalfheim ("The Dark World"): Home of the Dark Elves.
- Niffleheim ("Mist-Home"): Realm of the dishonored dead, a land of ice, mist, and cold.
- Hel is a region of Niffleheim where the dead who are neither honored nor dishonored.
- Muspelheim (Muspel): Home of the Fire Demons, a realm of eternal fire.
- Heven: Home of the Angels. A paradisal realm, Heven was cut off from the other nine by Odin during a brutal war against Asgard. It was reopened by Thor and Loki.