Katherine Pierce is a young woman with whom both Damon and Stefan Salvatore fell in love. However, she was revealed to be a vampire with a cold and calculating personality. She had plans to turn both Stefan and Damon into vampires and for the three to spend all eternity together. Her manipulation was one of the reasons that drove the two brothers apart.

Along with her vampire friend Pearl and her witch servant Emily Bennett, Katherine realized that the Founding Families of Mystic Falls knew that vampires were running around the town. However, despite Pearl's constant warnings, Katherine refused to abandon her plans with the Salvatore brothers. When she ingested the vervain in Stefan's blood (that his father had made him drink), she was captured by the townspeople and burned in Fell's Church with Pearl and 25 other vampires.

In 2009, Damon told Stefan that he had made a deal with Emily to cast a spell that would protect Katherine and keep her in a mummified state until he could wake her again. When Bonnie Bennett and her grandmother opened the tomb, Katherine wasn't in it. Pearl revealed to him that Katherine had escaped by compelling the guard that had been keeping them. Anna, Pearl's daughter, told him that she had never loved him and that she was no longer interested in him. Isobel had been said to have met Katherine shortly after she was turned. Katherine returns at the end of the season finale and is discovered making out with Damon, who is thinking he is kissing Elena. Jenna catches Damon and "Elena" (Katherine) kissing on the front porch and makes her come inside. Katherine goes into the kitchen and starts speaking with John, who thinks he's talking to Elena. She takes a knife and cuts off the fingers on the hand that has the ring on it (the ring that keeps him from being killed) and then kills him. Before he dies he says "Katherine" in a dieing voice. Elena comes home and starts to walk in the kitchen (because she hears a cling almost like a something fell) and then the episode is over.