Akhaten

Akhaten was a parasitic, sentient planet that fed on the souls, and therefore the stories, of the inhabitants of the seven planets in the system. He was considered by the people of these worlds to be a great and fearful god.

Biography
He slumbered for thousands of years, until the Long Song ended. Then, he awoke and threatened to consume all seven of its neighbouring planets. Eventually, the Eleventh Doctor let him take his memories instead of the valuable things of the natives of Akhet. The Doctor was then saved by Clara Oswald, who gave the Old God the leaf that told all of her family's story, all that happened, all that didn't happen and all that should have happen. The overload of stories caused him to implode. (TV: The Rings of Akhaten)