The leader of Libra and young head of the noble Reinherz family. A large, very powerful man with a distinctive underbite, he is actually very well composed and gentlemanly and honest to a fault, with an unshakable will. Master of the Brain Grid Blood Battle Style, which he can use to create large cross-shaped weaponry and seal away vampires.

Spoiler

The sealing power he owns is to seal away vampires only under a certain condition: knowing the vampire's real name.

Klaus is also very intelligent, being able to play the game "Prosfair," the complexity of which is known to drive humans mad (Klaus himself begins to bleed internally after playing the game for 99 hours without a break) and is a game usually reserved only for one distinct species in Hellsalem's Lot that has studied it for a thousand years.