The Vampire Diaries, an American supernatural drama, was officially renewed for a third season by The CW on April 26, 2011. The season aired from September 15, 2011, to May 10, 2012, and consisted of 22 episodes. The plot focused on the story of Klaus' origin, his relation with his family and revealed more about the Original family. The third season opened to generally positive reviews. The season takes a gap from the last season and begins with Elena Gilbert's 18th birthday, with all series regulars returning with the exception of Sara Canning, whose character, Jenna Sommers, was killed off in the previous season. Joseph Morgan's character Klaus became a series regular after previously appearing in a recurring role.

The Vampire Diaries, an American supernatural drama, was officially renewed by The CW for a full 22-episode season on February 16, 2010. The first episode premiered on September 9, 2010, at 8 p.m. ET. The season picks up immediately after the events of the season one finale. All the series regulars returned. The second season focuses on the return of Elena Gilbert's doppelgänger, Katherine Pierce, the introduction of werewolves, the sun and moon curse, and the arrival of the original vampires. Tyler Lockwood's uncle, Mason Lockwood, arrives in town searching for the moonstone, a family heirloom. Tyler later learns of his family's werewolf curse. Meanwhile, Caroline Forbes is killed by Katherine while having Damon Salvatore's blood in her system, turning her into a vampire. The arrival of the original vampires, Elijah and Klaus Mikaelson, also bring about complications. Klaus is a vampire-werewolf hybrid, but his werewolf side had been forced into dormancy by witches, as nature would not stand for such an imbalance in power. Therefore, Klaus arrives in town with plans to break the curse and unleash his werewolf side by channelling the power of the full moon into the moonstone, sacrificing a vampire and a werewolf, and drinking the blood of the doppelgänger. It became available on DVD and Blu-ray on August 30, 2011.