Castle Greyskull is a nexus of the power of the universe. It is the main goal in Skeletor's plans, and the thing from which He-Man gets his power.

The power sword was split into two halves, one is possessed by Skeletor, the other is possessed by He-Man, if the two swords are united, they become the key to the power of Greyskull.

The Sorceress is the keeper of Greyskull, it is she who empowered Adam to become He-Man.

Battle Cat is He-Man's Steed. He is a large green cat with battle armor (he is also a cat when He-Man is Adam, but he is gray and has no armor)

She-Ra (princess of Power) Started out as a toy for girls, then it got tied in to He-Man, increasing it's market. She-Ra is He-Man's Cousin, she exists in an alternate dimension, where her arch Nemesis is a man called Hordak