Vigil

The Vigil were responsible for the sacrifice of the Queen of Years, should she choose not to sacrifice herself.

History
The Vigil were part of the Alliance of Races founded by Rassilon to fight the Hyperions. After the Hyperions were defeated, the Vigil joined with the Alliance once more to purge the universe of threats to universal harmony. One such threat was D'if of the Cybock Imperium. The Vigil watched on with the rest of the Alliance as Rassilon defeated D'if in a game of Russian-roulette. (COMIC: Gangland)

Clara Oswald first encountered the Vigil when they were hiding in a storeroom. They were looking for Merry, who had run away due to her being scared. The same three Vigil attempted to fulfil their duties when the Eleventh Doctor and Clara Oswald protected the then-current Queen of Years, but disappeared after they had failed, as the Old God had no further need of them. (TV: The Rings of Akhaten)

A Vigil was among other guests aboard a submarine touring an underwater colony on New Oceana. (COMIC: Beneath the Waves)

Abilities
The Vigil had very soft voices, and were terrifying to most people who encountered them. In battle, they had powerful telekinetic powers which could be used to hurl their victims or shield themselves from attack. However, even when all three of them were attacking at once, they were unable to overcome the Doctor, who defended himself with his Sonic screwdriver, albeit he had some difficulty in doing so.

The Vigil also possessed the ability to teleport, which appeared to be their most common form of travel. (TV: The Rings of Akhaten)