Comet the Super-Horse was a pet horse belonging to Supergirl. Born as a centaur in ancient Greece, a witch had cast a spell on him that allowed him to switch between both forms. She also gave him a variety of other super-powers, including immortality. Whilst on a mission with Supergirl on another planet, he was given the opportunity to turn into a human, but only while a comet passed through the solar system. As a man, he adopted the identity of rodeo star "Bronco" Bill Starr. He was a member of the Legion of Super-Pets.