Realms

Realms are different planes of existence in all of creation. Most of the realms are were created by God. The realm primarily seen is the The Universe. The other realms created by him consist of Heaven, Purgatory, and Hell in that order which were created by God. However, Avalon and the Empty's creator is unknown.

Heaven
The realm of the angels and souls of humans deemed worthy to enter into its gates. Guarded by the angels of God and led by the archangels.

Purgatory
The realm of the monsters and Leviathans, a place filled with war, death, and chaos.

Hell
The domain of demons and souls sent there through the power of the deals. Houses hordes of dark souls and entities. It is also the location to Lucifer's Cage where it holds Michael and Adam.

The Universe
The realm of the humans, animals, monsters, creatures and Pagan Deities. It is the main realm.

Avalon
The realm of the fairies. House all fairies inside its own pocket dimension. Oz is also a branch of the fairy world.

The Empty
A realm where Reapers can send souls, rather than Hell or Heaven. According to the Reaper Billie, once a soul is send to The Empty, it can't be resurrected.

Trivia

 * Of the realms seen Hell is the only one seen in a dark demeanor reflecting its purpose as a place of torture.
 * Earth and Purgatory are the only known realms where everything is tangible and existent. Avalon is unseen and Heaven and Hell are mostly memory reflections or illusions of torture and pain.
 * Dean Winchester is the only known being to have been to all five realms of existence, while Sam, Castiel and Bobby have been to all but Avalon.
 * Heaven and Purgatory are the oldest of the realms, followed by either or Earth and then Hell. Paradise existed, soon chaos rolled in, and then when evil came Damnation was created.
 * The Earth realm has the most beings walk though its paths, Purgatory and Hell being second angels, monsters, demons, humans, and reapers/Horsemen. Heaven with the least angels, humans, and Horsemen.