The Disciples of the Light were a highly advanced civilization who, according to The Beast, lived before the universe was created in Doctor Who. The Beast identified himself as Satan, Lucifer, Abaddon, etc. and was in battle with the Disciples for eons until they subdued and buried it on a planet later called Krop Tor, intending to leave it chained there for all eternity. Both the planet and K37 Gem 5, the black hole it orbited, served as a prison for the Beast.