[edit] Fictional character biography

In the illustrated books released with the first series of toys, He-Man is a barbarian from an Eternian tribe. The planet's inhabitants are dealing with the aftermath of the Great Wars, which devastated the civilizations that once ruled supreme over all lesser beings. The Wars left behind advanced machinery and weaponry known only to select people. An early incarnation of the Sorceress of Castle Grayskull gives He-Man some of these weapons, and he sets out to defend the secrets of Castle Grayskull from the evil villain Skeletor.

By the time the Filmation series was being developed, He-Man's origins had been revised as follows: his true identity is Prince Adam of Eternia, son of King Randor and Queen Marlena who live in the palace of Eternos along with Adam and the rest of their inner circle. Marlena was a lost astronaut from the planet Earth. The Sorceress of Castle Grayskull endows Prince Adam with the power to transform into He-Man, which Adam does by raising his Power Sword and proclaiming: "By the power of Grayskull...I have the power!". The original He-Man and Skeletor figures came with matching swords that could connect together, the concept of the two halves of the Power Sword was dropped in most of the media.

Prince Adam's pet is a cowardly green tiger named Cringer. While Adam is He-Man, Cringer can become a giant, brave armored green tiger named Battle Cat, assuming He-Man decides to hit him with the magical power cast from his sword. Battle Cat serves as He-Man's steed and fierce fighting companion; like He-Man, he was created prior to his alter ego.

Adam is friendly with the beautiful and strong-willed Teela, the adoptive daughter of his mentor Duncan. Adam and Teela grew up together and now, as Captain of the Guard, Teela is entrusted to protect the prince. She often sees Adam as lazy and cowardly because she is unaware of his alternate identity as He-Man. Teela is revealed to be the only daughter of the Sorceress and the future inheritor of Grayskull; the Sorceress gave her up for adoption after Teela's father died, when Teela was just a baby.

Duncan, also known as Man-At-Arms, is the Eternian royal family's innovator of technology and weapons. In many episodes, Man-At-Arms unveils new and fantastic weapons that help He-Man and his friends.

Castle Grayskull, which resembles a gigantic skull, is the source of He-Man's powers. Inside the Castle lives the Sorceress, who grants Prince Adam his transformative abilities, and communicates telepathically with He-Man. She also created He-Man's harness from a rare Eternian mineral called Korodite, which adds to his physical strength.

To protect his family, He-Man keeps his double identity secret, sharing the knowledge only with Man-At-Arms, Orko, Cringer/Battle Cat, and the Sorceress; with the advent of the She-Ra: Princess of Power series, this list is expanded to also include Adora/She-Ra, Spirit/Swift Wind, Light Hope, Loo-Kee, Madame Razz, and Kowl. The original cartoon series also includes the dragon Granamyr, the cosmic enforcer Zodak and at the end of a later episode, "The Rainbow Warrior" it is lightly hinted, although never confirmed or played on, that Queen Marlena may possibly also know his secret. He-Man is usually accompanied by an assortment of allies in his battles, such as Ram-Man and Stratos.

Later it is revealed that Adam has a twin sister, the Princess Adora, a leader in The Great Rebellion against Hordak on the planet Etheria. Adora, like Adam, is given the gift of the power of Grayskull and has her own sword which she uses to transform into She-Ra, Princess of Power. He-Man makes a number of appearances in the She-Ra: Princess of Power television series.

He-Man's chief adversary is Skeletor, a blue-skinned sorcerer with a skull for a head, wearing a cowl. He is skilled in black magic as well as all forms of combat. Skeletor's weapon of choice is his Havoc Staff, a ram's skull atop a large rod, which serves to channel his magic and amplify his powers. The Havok Staff also allows Skeletor to engage in the remote viewing of events on and around Eternia. Though his origin is mysterious, and the cartoon describes him only as a "demon from another dimension," a tie-in comic implies that Skeletor's true identity is Prince Keldor, younger brother of King Randor, thus making him He-Man's uncle. It is revealed in the He-Man motion picture He-Man and She-Ra: The Secret of the Sword that Skeletor was Hordak's right-hand man up until his capture, and supposed release.

Skeletor's base of operations is Snake Mountain, a fortress made of polished black basalt,^{[citation needed]} which has a giant stone snake coiled around it. Snake Mountain is located on the Dark Hemisphere of Eternia. Skeletor leads a motley crew of henchmen against He-Man and his associates; the most popular are the sorceress Evil-Lyn, the bumbling lord of the animal world Beast Man, the bionic Trap-Jaw, multi-sighted Tri-Klops, and fish lord Mer-Man.

In the 1980s series, He-Man/Adam is voiced by John Erwin, for many the definitive He-man, a congenial hero with an endless supply of one liners. In the 1987 live-action feature film, he is played by Dolph Lundgren. Gary Chalk provides the voice of He-Man for the 1989 series The New Adventures of He-Man, and later the voice of Man-At-Arms for the 2002 series. He does not provide the voice of Prince Adam; Adam is instead voiced by Doug Parker, unlike the 1983 and 2002 series, where Adam and He-Man were voiced by the same actor. In the 2002 series, He-Man is voiced by Cam Clarke.

According to Lou Scheimer, executive producer of the Filmation animated series, the idea of He-Man having a teenage alter-ego was derived by from the Fawcett/DC Comics character Captain Marvel, about whom Filmation had already produced two TV series: Shazam! and The Kid Superpower Hour with Shazam!. He-Man's twin sister She-Ra was created as a female spin-off, as Captain Marvel's twin sister Mary Marvel had been.