Guardians of Time

The Guardians of Time Powerful conceptual entities who embodied the concept of Light and Order The White Guardian and Darkness and Chaos The Black Guardian. They maintained universal balance through an artefact known as The Key to Time. The existence of the Guardians was known only to a few species, among those were the Time Lords' High Council and The Eternals, who called them Enlighteners. The White Guardian enlisted the help of the Fourth Doctor to gather the six segments of The Key to Time in order to restore the universal balance of the universe The Ribos Operation. Eventually, The Doctor succeeded and assembled The Key, outwitting The Black Guardian and allowing The White Guardian to restore balance. The Armageddon Factor The Black Guardian later used Turlough to try and kill the Fifth Doctor. Mawdryn Undead, Terminus The Black Guardian tried to offer the prize of Enlightenment to The Eternals, but was thwarted by the Fifth Doctor. The two Guardians will exist until neither is needed any longer. Enlightenment