The Defenders were a group of previous Masters of the Universe led by Captain Randor to defend the Council of Elders and Hall of Wisdom from Keldor's forces during the Great Unrest. Little is known about their normal operations as they only appear in one episode of Masters of the Universe.
The Defenders went to the Hall of Wisdom to warn the Council of Elders of an imminent assault from Keldor and his forces . Captain Randor was convinced that the Elders would be vanquished and Keldor would gain all of the power in Eternia if they did not evacuate immediately. The Elders knew of Keldor's oncoming attack and assured Randor that his forces would overcome them. The Elders did indeed leave the Hall, but not before appointing Randor to be King over Eternia in their stead. Before Randor could argue that he is not fit to be King, Keldor's forces broke through a wall and engaged the Defenders. The Elders vanished and the newly anointed King was left to battle Keldor. Randor was able to defeat Keldor, who threw a vial of acid at the King in a desperate last attack. Randor deflected the acid and it instead landed on Keldor's own face, who was promptly rescued by Beast Man. After seeing that they were defeated, Trap Jaw called for retreat. He and the rest of Keldor's forces followed Beast Man and their leader, with the Defenders in pursuit.
The Sorceress of Castle Grayskull then telepathically informed Randor that his forces would be successful in pushing Keldor's forces back to the Dark Hemisphere, Eternia would experience peace for a time, and a hero would emerge when needed. Randor asked how he will know this hero, but received no answer.
The Defenders were seemingly disbanded some time after this encounter, seeing as Randor now has duties as King, and Eternia is at peace for the time being.
- All of the Defenders are drawn younger than their future appearances as Masters. The two most noticeable changes in design are Man-At-Arms' lack of a mustache and Stratos' lack of a beard.
- In the script for The Beginning Part 1, released on the Complete Series DVD collection, Roboto is also mentioned as being present, but cannot be seen at any point during the completed episode.