Ancient Lights
The Ancient Lights are peace-obsessed energy entities which were able to disobey the physical laws of the universe using the power of astrology, they also use it to channel their power into other lifeforms giving them powers while also controlling them.
Biography
Luke Smith speculated that the Ancient Lights originated from before the universe. Martin Trueman said that the Lights had existed for at least thirteen billion years and, seemingly confirming Luke's theory, that they had survived the Big Bang. The Ancient Lights' powers derived from the Zodiac and from birth dates, of no significance in N-Space, though fundamental to the workings of the Lights. Their powers operated in such a way that Mr Smith could not detect them, as if they did not exist at all. According to Trueman, the purpose of the Ancient Lights was control.
Though they had existed for billions of years, they needed the stars to be right to act. One of The Lights manifested on Earth in 2009 as a comet-like stream of orange light to possessed Martin Trueman, who had a special destiny. His birthdate had said he would act as channel for the Lights. Using the Lights' power, Trueman could tell people's names, command them to do small tasks, and shoot deadly energy beams from himself. Foremost among his powers, he could transfer the power of the Lights onto others, which, in effect, acted as a kind of mind control.
He built a career for himself, using the powers granted to him by the lights. The Lights' power depended on astrology. Luke, who had no birthdate, had an immunity to the Lights' power. The Lights depended on a certain conjunction of all the stars in the universe to possess all of Earth, in order, according to their star signs. They had proceeded up to Aries, the next-to-last sign of the Zodiac before the completion. When Luke Smith broke their power, they either destroyed Martin Trueman or turned him into one of them and returned into space. (TV: Secrets of the Stars)
Behind the scenes
Secrets of the Stars was originally going to use the Mandragora Helix. However, it was decided that "Mandragora had to change too much, and was too easily defeated, in order to fit this plot" and the Ancient Lights were created instead. Russell T Davies has said he likes to think both entities are "distant cousins". (DWMSE 23)