Nessican

Nessican was an infamous vampire assassin. He was once imprisoned in a phantom sun.

Along with fellow vampire Cain, was sent to Earth — a planet with which he had not previously had any familiar — by Tannis to investigate the sources of mysterious temporal distortions which had been perverting the course of history, and kill anyone else who might know this secret. This quest led to him tracking down two of the surviving Time Lords, Valentine and Antenor, a couple known as "the Saints". He murdered them both, draining their blood, then fled into the sewers, where he recorded a report to Tannis, explaining that he had killed the Time Lords but not managed to learn of the distortions' origins. He was then tracked down by the Seventh Doctor and police inspector Speedwell. The Doctor had recently eaten garlic and tricked Nessican into fatally poisoning himself when he tried to feed on the Doctor. (WC: Death Comes to Time)