The Milky Way Galaxy is a spiral galaxy that is said to be over 250 million light years in diameter, and contains 200 billion stars. (DW: "Doctor Who", SJA: "Secrets of the Stars") It was known to the Time Lords as the Stellian Galaxy. (DW: "The Mysterious Planet")
The Milky Way Galaxy (top-left) as part of the tri-galactic
During the period of the Dark Empire (circa 1009 BC), the galaxy was tyrannically ruled by a mysterious and reportedly immortal entity called Horath. A cybernetic organism that could command the physical laws of the universe, Horath crushed the civilisations of all but the most primitive planets. Although he was ultimately defeated, Horath could not be killed so his body and his consciousness were divided and hidden at opposite ends of the galaxy. (SJA: "Enemy of the Bane")