He-Ro was planned to be an intriguing new character introduction, the centerpiece of "The Powers of Grayskull", a spin-off line of Mattel's Masters of the Universe toy line in 1987. "The Powers of Grayskull" was to be set in Eternia's prehistoric past, called "Preternia" to differentiate, and promised to reveal secrets about the source of He-Man's power, through the adventures of He-Ro, a young but powerful wizard who lived in that time. However, the line was cancelled in early 1987, and none of this came to fruition. The 1987 Mattel Toy Catalog published pictures of the proposed toys from the "Powers of Grayskull" line, including an action figure of He-Ro, of course. Three of the dinosaur toys from the line actually made it to stores, and the two "giant" action figures saw release as exclusives in Italy, but He-Ro was never released as a toy. Though much has been speculated concerning the character in the intervening years by fans of the He-Man franchise, He-Ro remains as much a mystery today as he was in 1987, when a perplexed He-Man was forced to ask, "But who is he?"
"Travel back in time through a secret time portal--and discover the ORIGIN of THE POWERS OF GRAYSKULL! Learn how He-Man became so strong! And explore the magical world of Preternia--home of HE-RO, the Most Powerful Wizard in the Universe! Monstrous dinosaurs and fierce giants--both good and evil--struggle for control of this strange & hostile land! The dinosaurs in the time of Grayskull--Tyrantisaurus Rex, Bionatops and Turbodactyl--each possess a fantastic mechanical power! Can HE-RO master all the good magic of the Ancient Wizards, and protect future Eternia from forever falling in the claws of evil? Look For HE-RO and The Powers of Grayskull coming your way in 1987!"
This brief overview set the stage for the Powers of Grayskull storyline, and was elaborated upon in the mini-comic The Powers of Grayskull - The Legend Begins!. This book was intended to be the first of a three-part mini-comic mini-series, revealing the whole He-Ro story to the toy-buying public. However, only this first installment appeared, the last mini-comic produced.
As the story opens, the Sorceress uses the power of Central Tower to take He-Man on a fact-finding tour into Eternia's distant past. When the Sorceress and He-Man arrive, followed by Skeletor, they find King Hiss leading a Snake Men attack on a village in the hope of drawing out "The Elders", using some of the cybernetic dinosaurs to their advantage. Hiss serves an "unnamed one" and agrees to unite with Skeletor on the basis that he might be an emissary. Seeing Skeletor's interference, the Sorceress allows He-Man to enter the battle but "for reasons that will be made clear to you in the future" he had to be disguised. He finds himself overwhelmed, but then a shadowy figure appears who turns the odds with a powerful wand. The stranger then sends the Snake Men back to their base and all the time travellers home. The Sorceress describes the intervener as "the Greatest Sorcerer of all!" and He-Man is left asking "But who is he?"
Beyond this, very little information of the backstory was developed, though many fans have produced their own theories and continuations.
During the 1990s, Lou Scheimer, producer of the original He-Man cartoon series, produced a series bible for a MOTU sequel series submitted to DiC Entertainment. The series was named "He-Ro, son of He-Man and the Masters of the Universe", which would occur years after the original series and would feature Dare, the adopted son of King Adam and Queen Teela, who could transform into He-Ro to face the return of Skeletor, who was imprisoned years ago by He-Man and The Sorceress. The character was unrelated to the original "He-Ro" concept. Although several writers from the original series, notably Larry DiTillio, expressed interest in writing for the proposed series, the idea was shelved after DiC showed little interest.