Prince Adam of Eternia transforms with the Power Sword into He-Man, the Most Powerful Man in the Universe. Sworn defender of the secrets of Castle Grayskull, twin brother of She-Ra, and chief opponent of Skeletor.
He-Man is the alter ego of Prince Adam, son of King Randor and Queen Marlena of Eternia. When Adam raises his Power Sword and speaks the invocation “By the power of Grayskull. I have the power!” he is transformed into He-Man, the Most Powerful Man in the Universe. The transformation also turns his cowardly tiger Cringer into the armored, fearless Battle Cat.
He-Man and his allies defend Eternia, the secrets of Castle Grayskull, and the universe from the schemes of his archenemy Skeletor. To protect his family, He-Man keeps the double identity secret, sharing the knowledge only with Man-At-Arms, Orko, the Sorceress of Castle Grayskull, and Battle Cat. With the arrival of the She-Ra: Princess of Power continuity, the circle widened to include his twin sister Adora, Light Hope, Madame Razz, and a small group of Etherian allies.
The character’s published origin has shifted across continuities. In the 1982 DC mini-comics by Donald F. Glut, He-Man is an Eternian barbarian who receives his weapons from an early incarnation of the Sorceress and possesses one half of the Power Sword, with Skeletor wielding the other; the two halves combine into the key to Castle Grayskull. The 1983 Filmation series replaced this with the Prince Adam dual-identity premise that became the canonical form of the character. The 2002 MYP reboot kept the Adam identity but added a backstory tracing He-Man’s power back to King Grayskull, an Ancient who originally wielded the Sword of Power.
Across his appearances He-Man has been portrayed as a leader of the resistance against Skeletor, a strategist who prefers nonviolent resolutions when possible, and a hero who explicitly avoids killing. His strength is consistently shown as the defining trait. The introduction sequence of the 1983 series memorably catalogs his immediate companions and the source of his power, an enduring template that later series have echoed.
Catalogue source: heman.fandom.com (CC BY-SA 3.0).