Pulled into E-Space, the Hydrax landed on a primitive planet. Sharkey and two other human officers were turned into vampires by the King Vampire. Gaining immortality, they ruled the peasants from the tower for a thousand years. They kept the population in constant fear of the Wasting King, with Camilla as his queen, and Aukon as his advisor. Over the years, Sharkey became known as "Zargo" and forbade all knowledge.
Zargo died when the Fourth Doctor launched one of the shuttles from the Hydrax into the heart of the King Vampire, causing Zargo, Aukon and Camilla to lose their immortality. They quickly aged to death. (TV: State of Decay)