Eternia is the name of the fictional planet that serves as a setting for the Masters of The Universe toy collection and animated series.

The original concept of Eternia was that it was a world with a barbaric civilization, except that it had SOME advanced technology (such as vehicles) as well as powerful magic (not a common feature in barbarian fiction.) In the animated series, the world's features and background were greatly expanded. Eternia came to feature an incredible variety of lifeforms (from monsters to sentient races, including nonhumanoid ones, such as ), natural and magical wonders, cultures, and hidden civilizations. And of course, it contains Castle Grayskull , which holds one of the greatest magical powers in the universe.

According to an episode of the first series, Eternia lays at the center of the universe. (Inside the planet's center laid the StarSeed, a spark left from the creation of the universe, that could grant infite power to its holder. Skeletor, after finding out about this, tried to obtain it, but He-Man got it first and, after resisting its corrupting influence, gave it to Zodak , who disposed of it.)

The oldest (still living) being on Eternia is a giantic sentient tree called Skytree. (The second oldest is Granamyr, ruler of the Dragons of Darksmoke, who has always envied the tree's status.)

Eternia's prehistoric era is known as "Preternia." It seems to have featured dinosaur-like monsters (including some bionic ones, of unknown origin) as well as cavemen. Some of these dinosaurs were preserved inside Eternia's Tar Swamp.

Some of Eternia's ancient civilizations possessed very advanced technology, and left many ruins and artifacts behind. An example is The Egyptian-like Osirians, who used to live in the Sands of Time.

It seems that a "Council of Ancients" who possessed great magical power, decided to store their power and wisdom on Eternia; this is what Castle Grayskull was built for. (In the 2002 series, it seems that the castle contains the very essence of the Ancients.) This is the source of He-Man's powers. It was also decided that a woman, to be known as The Sorceress, would be the Castle's guardian; apparently this is an office that is passed from mother to daughter. (In the original series, The Sorceress was not allowed to leave the Castle except in the form of a falcon; this was changed in the latest series.) The Castle is surrounded by a moat that seems to be an endless pit.

In the original series, Zodak was the last member of the Council; in the new version, he's a warrior from their time period.

It should be noted that He-Man is NOT the first person to wield the Power of Grayskull. One of Prince Adam's ancestors, also a King of Eternia, was granted the power to oppose the evil Snake-men, and their leader, King Hiss . He succeeded in trapping them within the petrified remains of their own giant, three-headed 'Snake God', which eventually became known as Snake Mountain (two of its heads eventually crumbled) which Skeletor would come to use as a base. (In the new series, the Snake Men were freed, and the 'god' temporarily revived.)

Also in the new series, the planet was separated into two regions by a huge magical wall, to keep Skeletor's forces at bay, but the wall was eventually broken.

Some of Eternia's features include:

-The Royal Palace of Eternia

-Castle Grayskull

-Snake Mountain

-The Evergreen Forest (a HUGE forest that is the planet's main source of oxygen)

-The Sands of Time (a huge desert)

-Subternia (the name for the subterranean portions of the planet)

-Darksmoke, mountain home of the Dragons

-The Tar Swamps

And several others.

Map of Eternia