Klaus von Reinherz is the leader of the secret organization Libra, which is dedicated to maintaining peace and order in Hellsalem's Lot, the chaotic city that was once New York. He hails from the noble von Reinherz family and was born in Bavaria, Germany. An encounter with a powerful Blood Breed pushed his body to the brink of vampiric transformation, but his immense strength of will allowed him to resist the final stage and retain his humanity, a feat that deeply influences his sense of duty. In personality, Klaus is a man of striking contradictions. Despite his massive, intimidating physique and a distinctive underbite, he is remarkably composed, gentlemanly, and honest to a fault. He conducts himself with unwavering calm and courtesy, though he is capable of erupting into beast-like savagery when the situation demands it. His intelligence is formidable, demonstrated by his ability to play Prosfair, an alien game so complex it can drive humans mad. He is driven by a deep-seated desire to protect both humans and the supernatural beings that inhabit his city, believing in the possibility of coexistence. As the leader of Libra, Klaus serves as its unmovable moral center and its greatest frontline warrior. He acts as a mentor and father figure to the protagonist Leonardo Watch, recognizing and nurturing his courage. He shares a deep, trusting partnership with his second-in-command, Steven A. Starphase, who handles the organization's darker logistics. Klaus also maintains a patient, stabilizing influence over the reckless Zapp Renfro. Throughout the series, Klaus remains a pillar of strength. His development focuses on the burden of leadership and his unwavering commitment to his principles. His backstory as a Fang Hunter and his resistance to vampiric corruption highlight his lifelong dedication to his cause. In combat, Klaus is the master of the Brain Grid Blood Battle Style, a technique that allows him to manipulate his blood into massive cross-shaped weapons and defensive barriers. His signature ability is the power to seal vampires, though this requires knowledge of the vampire's true name. Together with his incredible physical strength, tactical acumen, and indomitable will, Klaus stands as one of the most powerful and respected figures in the series.