He-Man in black magic and all forms of combat. He was also shown to be extremely cunning and intelligent. Though his origin was mysterious, and the cartoon described him only as a "demon from another dimension", a tie-in comic implied that Skeletor's true identity was Prince Keldor (the older brother of King Randor), thus making him He-Man's uncle. It was revealed in the animated motion picture "He-Man and She-Ra: The Secret of the Sword" that Skeletor was Hordak's right-hand man until his capture (Hordak referred to Skeletor as "my old pupil" and Skeletor's throne-room in Snake Mountain as "my old throne-room"
He-Man be a descendant of King Grayskull (a powerful barbarian and a hero from Eternia's ancient past), who sacrificed his life in order to save Eternia from the Evil Horde and originally wielded the Sword of Power. He was the original owner of Castle Grayskull; his sword was concealed in the castle for centuries before being given to Prince Adam, who inherited his ancestor's own power channeled through the sword (thus giving added meaning to the phrase "By the power of Grayskull..."). This action-figure line combined elements from the He-Man universe into a cohesive storyline with biographies on the figures' packaging.