Temporal anomaly

Having been brought to his personal future by the Time Lords, the Second Doctor explained to the Brigadier that he was a temporal anomaly. (TV: The Three Doctors)

The Dalek Combat Training Manual, published by the Time Lords during the Last Great Time War, noted Oswin Oswald as an instance of Clara Oswald, a temporal anomaly who had been keeping the Doctor alive for centuries. (PROSE: Dalek Combat Training Manual)