|This article is about Klaus from the novels. You may be looking for Niklaus Mikaelson from the shows or his deceased original counterpart.|
Klaus is an Old One, a pureblooded vampire and the strongest of all vampires. Klaus is one of the 'Old Ones' who has never been a human, and he existed long before the Pyramids were built, which was c. 2500 B.C. According to him, he fought in the Trojan War (a war started to reclaim Helen of Sparta — the namesake of Elena Gilbert — the most beautiful woman in the world from her from her Trojan captors) and helped cause the downfall of the Roman Empire. In the late 15 century, he lived in a village in Germany, where the people thought that he was the devil himself.
In another universe, Klaus was a central antagonist in the second part of the original novels by L.J. Smith and tormented Elena Gilbert and her friends before being subsequently killed by her twice, but due to Elena returning to the past to prevent events that would eventually bring him to town, a new universe and timeline was birthed and Klaus never came to town and therefore was never killed by the Principles.
Klaus is Nordic in appearance, with electric blue eyes and short, close-cropped, platinum blond hair. He is described as being very handsome although his features are often contorted in madness. He wears a dusty long tan coat.
Personality-wise, Klaus is extremely deranged, and the line between his evil and his madness are very blurry. When pressed, he is deadly serious and reminds everyone about his unfathomable old age, but usually he seems unnaturally chipper, and his evil deeds during Dark Reunion are tinged with irony. He refers to everyone as "sport." He writes "Goodnight, sweetheart" on Vickie's mirror after brutally murdering her and leaving the same song playing in her room. He nearly kills Stefan with the white ash wood spear that was intended for him. His mood changes from cheerful and amused to enraged in seconds. Despite his seemingly erratic and scattered personality, he appears to be a patient and methodical killer capable of elaborate plans.
Klaus is of unknown age, earliest memory is of carrying a bronze axe, placing his inception in the Bronze Age (4500 BC - 3200 BC). He fought in the Trojan War (1194 BC to 1184 BC), was part of Alexander the Great's army (336 BC - 326 BC) and witnessed the death of Julius Caesar on March 15, 44 BC, and in the wars that led to the Roman Empire's downfall (on the Germanic side) in AD 456. During this time, probably, he met and gained confidence of a being named The Devil, with which, later, signing a pact (probably why Guardian blood can kill him). He then, probably, decided to stick around the general area of Germany. In the late 15th century, he lived in a village in Germany, where the people thought that he was the devil himself. One day, a maid showed up and begged for his help, because her young mistress was dying. That girl was Katherine von Swartzschild aka Katherine. He then turned her into a vampire, feeding her with his blood, saving her from death and making her much stronger than she had been in life, and Gudren used more of her connections to find Katherine a spelled lapis lazuli ring so that she could walk in the daylight. Nothing more is known about Klaus' whereabouts when, one day, in 1491, Katherine return in the German village to find him, after faking her death in an attempts to get the Salvatore brothers to reconcile by fooling them into believing she had committed suicide. The two then spent the next five century together. The books suggest that Klaus abuses her while teaching her to become a significantly tougher, stronger vampire, and over time with Klaus influence, she becomes power-hungry and insane, losing utterly her childlike innocence and naiveté. At some time, however, Katherine eventually attempts to kill Klaus, evidently believing that she has succeeded, but Klaus survived. His vernacular suggests that he's spent a lot of time in modern America, though - certainly enough to pick up slang like "sport" and use it comfortably and casually, and know (and use with effective irony) the song "Goodnight, Sweetheart."
The following is uncertain of this Klaus:
Probably during this time, in June 6, 1977, Klaus found the home of hunter-slayers Fernando and Gabriella Sulez and killed their guards with one blow. He then attacked Gabriella's parents, killing her mother and driving her father to insanity. Klaus then made her children, Meredith and Cristian, drink his blood, which presumably had a spell cast on it to start turning them into aging vampires without having to die. Their parents came home and Klaus tried to take the children, but Meredith fought back and bit him, so he let her stay and taunted her parents, saying to feed her a tablespoon of blood a week if they wanted her to stay alive. Klaus then sent them a picture of Cristian every June 6 (the children's' birthday) until 1984 when they were 10. In each picture, he had fully elongated fangs like a real vampire, but he was still getting older, whereas Meredith only ever had "kitten teeth" since she was only getting the bare minimum amount of blood to survive. On June 6, 1991, the Sulez family received another photo of Cristian, possibly indicating that he had been killed and turned into a full vampire by Klaus.
Since the Katherine of his universe is still alive, Klaus is left without a reason to return to Fell’s Church.