Comet The Super Horse - Tumblr Posts

Comet is an equine animal companion of Supergirl on Earth AI. Supergirl named him Comet because of a comet shaped mark on his neck. During the Golden Age of human civilization Comet was a centaur named Biron. 

Circe gave him a potion that was supposed to turn him into a human, but instead turned him into a horse. Unable to reverse the transformation, she gave him incredible powers which just so happen to be exactly like the ones Kryptonians develop under a yellow sun. She also made him immortal. 

On an adventure with Supergirl to the sorcerer’s planet, a spell caused Comet to transform into a handsome human male, but only while a comet is passing by. As a human, Comet assumes the identity of “Bronco” Bill Starr, a rodeo trick-rider, who has no memory of being either a horse or a centaur. 

The first time Supergirl met “Bronco” Bill they had an intense love affair. But it ended when he lost human form. Both Supergirl and Comet are unaware of Comet’s human identity.

Comet is however aware of Supergirl's affair with Bill because he has telepathy.

"Bronco" Bill

"Bronco" Bill Starr is the human form of Comet, the Super-Horse. "Bronco" Bill is a rodeo trick-rider, who has no memory of being either super-horse. 

The first time Supergirl met “Bronco” Bill they had an intense love affair. But it ended when he lost human form. Both Supergirl and Comet are unaware of Comet’s human identity.