Prydon
Lord Prydon was a vampire in an alternate timeline in which Rassilon failed to defeat the Great Vampire. He had two children, Arcalia and Cassandra. He wanted to meet with Borusa, but Arcalia instead brought him Romana II. He tried to convert Romana into a Vampire; in doing this he could detect which house she came from by the taste of her blood. He also learned of Romana's previous meeting with the Great Vampire, alluding to a faint taint in her blood.
Prydon was slain after being severly weakened by Romana's blood, which contained a biological defence against vampirism ironicaly developed by the Prydon of the main timeline. Temporaraly vunrable Leela was able to drive a knife through prydon's heart, the other was destroyed by cassandra, using a sword given to her by Arcalia prior to the confrontation.
With prydons death, the transduction barrier was lowered using the great key, bringing daylight back to galifrey and spelling the end of Prydon's vampire hoard.
