Nadia Petrova

Nadia Petrova (Bulgarian: Надя Петрова) was a major recurring character of The Vampire Diaries. She was a vampire and a member of The Travelers who was Katerina Petrova's daughter, making her an ancestor of Elena Gilbert and a descendant of Amara. 
Although most of Nadia's life is unknown, she revealed that she had spent the last 500 years searching for her mother; it also wasn't known from which Original's sireline she attained her vampirism, though it would be fair to assume that it came from the still-surviving Originals (Elijah, Klaus or Rebekah). She was seemingly not very well accustomed to modern American culture, but was more versed in past history, as she knew about the story of Silas, Amara and Qetsiyah. She also knew a great deal about Katerina's life in the past centuries, even though she had supposedly never personally met her before the events of Original Sin.
As a human, Katerina implied that she had been traumatized by the loss of her daughter, and that finding out whether she was alive or not had been of great importance to her. Likewise, Nadia was just as desperate to track down her biological mother, even going so far as to have herself turned into a vampire to give herself more time to find her. To this end, Nadia became an associate of The Travelers, the community of witches from whom she was descended, and began to work with a Traveler named Gregor, who eventually became her lover. The two were tasked with finding the immortal Silas, who had recently been awakened from 2,000 years of desiccation, and whom the Travelers were determined to cure and kill. Soon enough, Nadia's true intentions of locating Katherine were revealed, with the two reuniting after over 500 years shortly afterward.
When it became clear that Katherine, who had been forced to take the cure by Elena Gilbertand had become human again, was quickly dying of old age, it was Nadia who had the idea for Katherine (who was technically a Traveler witch, even if she had never tapped into her powers) to use a Passenger spell to live on within her own vampire body. However, Katherine refused to take away her daughter's chance at life and instead became a Passenger in Elena's body, a decision that would later result in Nadia being bitten by the hybrid Tyler Lockwood when it became clear that Nadia was up to something. Dying from the bite and having no chance at locating a cure in time, Nadia ultimately died from her wound, but not before Katherine used Elena's vampire body and Dream Manipulation to show Nadia what could have been their perfect day in the 15th century, had Katherine been allowed to raise Nadia as she had wanted. Nadia's fate after the destruction of the Other Side remains unknown.
Nadia was a member of the Petrova Family.