Sun-Eaters

The Sun-Eaters are an extraterrestrial species of powerful creatures that feed off the energy of small stars, thus making them a sort of living bombs.

Overview
Sun-Eaters resemble black holes surrounded by multiple tentacles, they seem to be sentient, although with an animal-like intellect and are driven by their hunger. They can only feed of stars, thus filling their systems with thermonuclear reactions.

History
A baby Sun-Eater was found by Superman during one of his adventures. Eventually, he decided to keep it as a pet in the Fortress of Solitude.