Question: when are the originals introduced in the vampire diaries
Answer: Season two

title: The Vampire Diaries (season 2)
text: The Vampire Diaries (season 2) 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. Season two focuses on the return of Elena Gilbert's (Nina Dobrev) doppelgänger, Katherine Pierce, the introduction of werewolves, the sun and moon curse, and the arrival of the original vampires. Tyler Lockwood's (Michael Trevino) uncle, Mason Lockwood (Taylor Kinney), arrives in town searching