The Great Vampires, (also called the djinn) were a species of huge vampires from another reality. Central to Gallifreyan legend and history, they were accidentally unleashed into N-Space during the Dark Times and fought by the Time Lords in an Eternal War.
Great Vampires were actually emanations and avatars of a force of destruction known as the Yssgaroth. They could manifest in multiple forms, including stems of bloody thorns, tearing flesh from whole worlds; huge winged snakes with horns, many eyes, and wet, dripping skin; and clouds of smoke that would fill a planet's atmosphere and induce nuclear winter.
The Vampires needed to steal energy from other sources to survive. Just one was extremely powerful and could drain a whole planet of energy. With their incredible hypnotic powers, the Vampires could enslave entire planetary populations.
See also: