He-Man and the Masters of the Universe was an animated television series that ran from 1983 to 1985.
The show takes place on the fictional planet of Eternia, a planet of magic, myth and fantasy. The show's lead character is Prince Adam, the young son of Eternia's rulers, King Randor and Queen Marlena. Whenever Prince Adam uses the Power Sword, and when he holds it aloft and says the magic words "By the Power of Grayskull...I have the Power!" he is transformed into He-Man, the most powerful man in the universe. Together with his close allies, Battle Cat, Teela, Man-At-Arms and Orko, He-Man uses his powers to defend Eternia from the evil forces of Skeletor. Skeletor's main goal is to conquer the mysterious fortress of Castle Grayskull, from which He-Man draws his powers. If he succeeds, Skeletor would be able to conquer not only Eternia, but the whole universe.