The Hyperions were a race of sentient suns.
Biology
The Hyperions were a fusion of DNA, nuclear energy and hyper-intelligence. The final stage of their evolution made them burn up, the energies within them mutating out of control, leaving them on the verge of supernova. (COMIC: Terrorformer)
History
The Hyperions left their homeworld on a quest to enlighten the lesser races of the universe, to make it a better place.
As the Hyperions' evolution made them mutate into unstable beings on the verge of supernova, the Hyperions benevolence became malevolence. The Hyperions began to subjugate the races of the universe, before encircling their suns with a fusion-web. The Hyperions used the suns to prolong their existence.
The Time Lords, Silurians, Sontarans and other races formed an alliance to stop the Hyperions, and declared war. The war wiped out the Hyperions and destroyed Hyperios.
The Twelfth Doctor encountered a survivor of the war, Rann-Korr, on Isen VI. Rann-Korr wished to begin again his races' quest of conquering the universe. The Doctor defeated him by channeling the seas of Isen VI into Rann-Korr, killing him. (COMIC: Terrorformer)