The Sorceress is the mistress and guardian of the Secrets of Castle Grayskull, the source of He-Man's great power. With a vast knowledge of magic and history, she is among the wisest beings on Eternia. He-Man often seeks her counsel, especially when situations are at their worst. In the Filmation series, the Sorceress demonstrates saintly qualities such as humility and appears to other characters who are in need of guidance.
However, since her powers are tied to Castle Grayskull, they weaken when she leaves its walls. When she does need to travel, though, she generally assumes the form of a falcon known as Zoar.
The Sorceress is also the mother of Teela, childhood friend of Prince Adam and Captain of the Royal Guard, whose aggressive temperament is a far cry from that of her soft-spoken mother. When Teela was an infant, the Sorceress gave her to Duncan(Man-At-Arms), to raise as his own, because the Sorceress felt that Castle Grayskull was too dangerous a place for her daughter to be raised.
The real name of the current Sorceress is Teela Na. Her history is revealed in the episode "The Origin of the Sorceress", in which Morgoth, an old nemesis of the Sorceress returns and attacks Eternia. While waiting for Morgoth to reappear, the Sorceress explains to He-Man how she became the guardian of Castle Grayskull. Her home, the village of Nowella, was attacked, and subsequently conquered, by Morgoth and his allies Ferros, Repta, and Rachney, servants of the Evil Horde. With the aid of an old storyteller's rhyme (In barren places find ye hope/And where no water grows, no plant grows, no wind blows/Find all you need...), Teela Na sought out Castle Grayskull, which she hoped would help her find a way to defeat her captors. Just as she was about to succumb to the Eternian wastelands, the mystical fortress appeared before Teela Na's eyes, and she was invited inside by a mysterious voice. Once inside she came across an old woman named Kuduk Ungol, her predecessor as the Sorceress. Kuduk invited her to take up the mantle of Castle Grayskull's protector, and explained her duties as such:
It will not be an easy task, Teela Na. You will fight many battles, see great sadness, and great joy. As Keeper of Castle Grayskull you must fight a constant war against evil, and comfort those in need. And, you will never be mortal again. Finally, you must preserve and protect the Swords of Power, until the day comes when they may be claimed.
Teela Na accepted the offer and immersed herself in the Pool of Power, which imbued her with the powers of Castle Grayskull. Once she had taken her place as the guardian of Castle Grayskull, the Sorceress returned to Nowella and overthrew the invaders before returning to her new home inside Castle Grayskull.