Katherine Pierce

Katerina Petrova (Bulgarian: Катерина Петрова), better known as Katherine Pierce, is a witch of the Traveller subculture, the third doppelgänger of Amara, a former vampire, a major antagonist and one of the main characters of The Vampire Diaries. She was the main antagonist of Season One (through John Gilbert's and Isobel's actions, as both were working for her), and one of the antagonists of Season Two. She was also a recurring character in the Third and Fourth seasons. Finally, she has a main role in Season Five.

After giving birth to a baby girl out of wedlock around age 17, and being forced to give the baby up for adoption, she was disowned. She was exiled to England, where she quickly assimilated into her new culture and met two nobleman brothers, Niklaus and Elijah Mikaelson. At first, she was attracted to the two brothers. However, she later learned that she was a Petrova Doppelgänger, and that Klaus was planning on using her as a sacrifice in order to break the curse that bound his werewolf side. She sabotaged his plan by running away with the moonstone, which bound the curse, and then tricked Rose into feeding her her blood so she could turn herself into a vampire. Because Katherine was no longer human, she was no longer a candidate to break the curse. Klaus was so infuriated with Katherine's sabotage, that she was forced to live on the run for over 500 years as he hunted her down.

Her activities during her first centuries as a vampire are unknown, but at some point between the 15th and 19th centuries, she took on the alias Katherine Pierce (which is an anglicized version of her birth name), and eventually met and befriended Pearl, Anna, and Emily Bennett. In the late 19th century, she traveled to Mystic Falls, where she met Stefan and Damon Salvatore while they hosted her at the Salvatore Estate. She later fell in love with both brothers, and subsequently turned them both into vampires. When the Town Council found out the identities of the vampires in town, she faked her death and escaped being sealed in the tomb, with the aid of George Lockwood, who helped her in exchange for the moonstone.