Libra
From Tardis Wiki, the free Doctor Who reference
Libra was a constellation visible from Earth and a sign of the Zodiac. (TV: Secrets of the Stars)
In 2009, the "Children of Libra" were the fourth to be brought under the control of the Ancient Lights when Martin Trueman invoked the sign into his circle. Among the Children of Third was Trinity Wells. Leo followed Leo and preceeded Scorpio. (TV: Secrets of the Stars)