|Series:||The Vampire Diaries|
|Location:||New Orleans, Louisiana|
Niklaus "Klaus" Mikaelson is the protagonist of The Originals. He is a former main character, antagonist/anti-hero of The Vampire Diaries. Klaus is an Original vampire and a werewolf, making him the Original Hybrid.
Klaus is the son of Ansel and Esther Mikaelson and the step-son of Mikael. He is the maternal half-brother of Elijah Mikaelson, Rebekah Mikaelson, Kol Mikaelson and Finn Mikaelson, Henrik Mikaelson and Freya Mikaelson. He was the uncle of an Unnamed Nephew. Klaus is the father of Hope Mikaelson, the mother being Hayley Marshall. He is also the adopted father of Marcel Gerard. Due to his werewolf gene, Klaus is a distant relative to Cary.
Klaus was first mentioned in the second season of The Vampire Diaries in Rose, during a conversation between Rose and Stefan Salvatore. Rose warns Stefan about the Original Vampires which led to Elena Gilbert believing Klaus was the oldest vampire in history. Elijah later mentions that Klaus is a recluse and trusts very few people, usually only in his inner circle. 
For over a thousand years, Klaus had been trying to break a curse placed on him. He created the myth of the sun and moon curse in order to find the moonstone and the Petrova Doppelgänger, both of which were needed to break the actual curse. His goal was to liberate his werewolf side so he could sire his own super species of vampire-werewolf hybrids. In 1492, he finally got the chance to break his curse when he met Katerina Petrova, the final piece necessary to break the curse. However, Katerina managed to foil his plan to use her in the sacrifice by turning into a vampire. For the next 500 years, Klaus searched for a way to break the curse without the doppelgänger, forcing generations of witches to help him. During his search for a way to break the curse, Klaus hunted down his family and neutralized them. He also hunted Katerina, who had escaped him and stolen his moonstone. However, it should also be noted that he was also on the run from his step-father, Mikael, as Klaus had an abusive childhood.
Besides his family, during the 1920's, Klaus formed a strong bond and brotherly relationship with Stefan. He then met with the vampire, Caroline Forbes, and starts to care about her eventually falling in love with her and tried to win her love, after a long time they are now friends. In New Orleans, he has a father/son bond relationship with Marcel whom he works with in ruling New Orleans until Klaus discovered his treachery for bringing Mikael to New Orleans. They reformed their friendship when Marcel saves his daughter and now they work together to bring down their enemies. He also truly cares about the bartender Camille O'Connell, whom he has a close relationship with.
Klaus is also the first undead creature in the history of the series universe known to have impregnated a woman. He was under the curse of the Moonlight Ring's forged with his blood, meaning that every werewolf who draws on them to prevent their transformation on the full moon will be drawing energy from Klaus himself. The Moonlight Rings forged from Klaus' blood have been destroyed so he no longer is weak every full moon.
Klaus is a member of the Mikaelson Family, and a member of an unknown Family of Werewolves. He is connected to the Labonair Family, a royal werewolf family via his daughter, and a member of the North East Atlantic Pack.