By the Power of Grayskull! I have the power!
He-Man is the chief protagonist of the Masters of the Universe franchise and is a space-age warrior who defends his world and others from the forces of the warlord Skeletor, who also happens to be one of the universe's most powerful and feared dark magicians.
Prince Adam was granted the power of the Castle Greyskull in order to defend the world of Eternia with fantastic strength against evil forces.
He-Man is actually Prince Adam, son of King Randor of Eternia. His powers come from a blessed sword that when utilised by the hero grants him the legendary power of Greyskull by which he can defeat almost any threat (in the live-action film using this sword He-Man was powerful enough to battle Skeletor when the mad dictator had attained literal godlike status).
He-Man, along with his pet tiger Battlecat and the other Masters Of The Universe, has become an icon of sorts and has spawned many cartoon series, TV shows and movies based around the subject - he is also the main character of the hugely successful toy line from which these adventures derived.
He is voiced by Cam Clarke, who also voiced Leonardo in the 1987 Teenage Mutant Ninja Turtles series.
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!"
Prince Adam's pet is a cowardly green tiger named Cringer. When Adam becomes He-Man, he similarly transforms Cringer into a brave armored green tiger named Battle Cat. 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 chose adoption for Teela after her father died, when she was just a baby.
Duncan, also known as Man-At-Arms, is He-Man's closest companion and the Eternian royal family's innovator of technology and weapons. In many episodes, Man-At-Arms unveils new and fantastic weapons or devices that help He-Man and his friends.
Castle Grayskull 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. The episode "Evil-Lyn's Plot" reveals that she also created He-Man's harness from a rare Eternian mineral called Coridite, 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 and the cosmic enforcer Zodac being in on He-Man's secret. The episode "The Rainbow Warrior" also strongly hints that Queen Marlena has worked out He-Man's secret but will not admit it. He-Man is usually accompanied by an assortment of allies in his battles, such as Ram-Man and Stratos.
The spin-off cartoon series She-Ra: Princess of Power later 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 She-Ra: Princess of Power .
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. 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, older brother of King Randor, thus making him He-Man's uncle. It is revealed in the animated 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 is accompanied by a group of henchmen who aid with his evil schemes.
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.
To tie-in with a new line of revamped figures based upon the original toyline, a new He-Man cartoon series was produced in 2002-03 by Mike Young Productions, again titled He-Man and the Masters of the Universe. This series retold the MOTU story from scratch. He-Man's origin was told in a 3-part episode that began the series, in which the 16-year-old Prince Adam is summoned to Castle Grayskull by the Sorceress to take upon the identity of He-Man and the role of Eternia's defender. The portrayal of his character in this series was mostly consistent with Filmation's portrayal, although the character of Prince Adam was shown to be much more brash and youthfully energetic than his 1980s counterpart, to convey the image of a teenage boy saddled with the overwhelming responsibility of defending the entire planet from evil.
The second season episode "The Power of Grayskull" also revealed He-Man to be a descendant of King Grayskull, an all-powerful barbarian hero from Eternia's ancient past, who sacrificed his life to save Eternia from the Evil Horde and was the original wielder of the Sword of Power. He was the original owner of Castle Grayskull, and his sword was concealed in the castle for centuries before being given to Prince Adam, who inherits his ancestor's own power which is channeled through the sword (thus giving an alternate meaning for the phrase "By the Power of Grayskull").
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.
In 1987, Cannon Films produced a live-action film Masters of the Universe which features Dolph Lundgren in the role of He-Man. Although the film was not received well upon its release, it has developed a strong cult following over recent years.
Although generally portrayed in much the same manner as other media, there were several notable differences in the character of He-Man within the movie. His additional use of a gun in several scenes, rather than only his characteristic sword, caused controversy among some fans. Also, there was no mention of his secret identity of Prince Adam within the film, which some fans have interpreted as an implication that the makers envisioned him as having only one permanent identity, as in the early mini-comics. He is portrayed as a widely recognized hero, regarded as a great leader and Eternia's best hope of survival.