Black Star Shenron is the third and final Eternal Dragon introduced in Dragon Ball. Like Shenron and Porunga, he too can only be summoned using a particular collection of Dragon Balls, the Black Star Dragon Balls.
Like the original incarnation of Shenron, Black Star Shenron is only capable of granting a single wish, however his capabilities greatly outclass those of his Eternal Dragon brothers. For instance, death wishes do not exceed Black Star Shenron's power. After a wish has been granted by the deity, the Black Star Dragon Balls are catapulted throughout the galaxy rather than their respective planet, and a one-year countdown is issued for the host planet's destruction which can only be undone if the Dragon Balls are returned to that planet within this time. In Dragon Ball GT, Black Star Shenron is used to cause Goku's body to physically regress to childhood, in a wish accidentally made by Emperor Pilaf. He is later summoned by Baby in the episode "The Game After Life", where he is instructed to restore Planet Vegeta (renamed to the "Tuffle Planet") and relocate it to Earth's solar system.
An interesting aspect of Black Star Shenron is his size. While Shenron and Porunga are both shown to be comparable in size to a large skyscraper, Black Star Shenron is shown to dwarf each of these Eternal Dragons combined. As a size reference, while coiling Shenron has been shown as being roughly the size of Kami's Lookout. Black Star Shenron on the other hand is so large that his head alone is roughly the size of the lookout. Black Star Shenron's appearance is also similar to that of a traditional Japanese dragon, while Shenron bares a resemblance to Chinese dragons. Another interesting difference is that the Shenron has his "whiskers" on the upper part (like a moustache) of its mouth while Black Star Shenron has them on the lower part of its mouth (like a beard).