Old God

The Old God was a parasitic, sentient star that considered by the surrounding species of Akhaten to a great, fearful god. he slumbered for thousands of years, until the Long Song ended. Then, he awoke and threatened to consume all the system's seven planets. Eventually, the Doctor let him taking his memories instead of the Akhaten's natives' valuable things. The Doctor was than saved by Clara, that gave the star the leaf that told all of her family's story, which she kept since she was a little girl. (TV: The Rings of Akhaten)