In the Filmation animated series, Miro ruled as the king of Eternia until he mysteriously disappeared, forcing Randor to take up the crown. Decades later, Miro was found and rescued, but he declined to resume his royal duties so he could learn about how the world had changed in his absence. Miro is still recognized as king, although Randor remains the sole head of the monarchy.
Because the 2002 animated series presented Randor as a common man who is named king by the Council of Elders, Miro was never king in this version of continuity. Instead a character appears named Captain Miro, implied to be the same person.