Lockhart is a Vampire King recognisable through his possession of a hat. Whether this hat has any magical properties or is merely a fashion statement is thus far unknown.
In time immemorial, four Vampires gained the ability to shackle spirits. These four (Vladimir, Swayne, Hastings and Lockhart) became the Vampire Kings and used their power to wipe out all other Vampires and then divide the continent among them - Vladimir in the North, Swayne in the West, Hastings in the South and Lockhart in the East. They then began warring amongst themselves for shackles, naturally.