* ActingForTwo:
** Paul Wesley is portraying Stefan, one of the three central protagonists. [[spoiler:In Season 4, it's revealed Stefan's ancestor is Silas and he is Silas' doppelganger. It's revealed in Season Five, there is one other doppelganger of Silas' alive in the present day, Tom Avery, an innocent paramedic.]]
** Acting for four in Nina Dobrev's case. She portrays Elena the protagonist, also Katherine a villain and one of the major antagonists. In Season Five Nina Dobrev also portrays Amara, the original Petrova, and Elena and Katherine are her doppelgangers. On the spin-off [[Series/TheOriginals]], she portrays Tatia in flashbacks to the 10th century and Katherine' is ''her'' doppelganger.
* ActorAllusion:
** Mia Kirshner, who plays a vampire, also starred in the early 90's series ''Dracula''.
** Jack Coleman plays [[Series/{{Heroes}} the father of a blond-haired girl with supernatural powers]]. He also hunts people with similar supernatural powers.
** David Anders was able to [[Series/{{Heroes}} come back from the dead before]].
* ActorSharedBackground: Katherine is originally Bulgarian, as is Nina Dobrev.
* CastingGag: Creator/PhoebeTonkin (Hayley) and Creator/ClaireHolt (Rebekah) were both main characters in ''Series/H2OJustAddWater''.
** Mia Kirshner, who plays Isobel Flemming, [[spoiler:Elena's real birth mother,]] played the role of a woman named Catherine in Film/{{Not Another Teen Movie}} (granted, spelled differently from our Katherine).
* DawsonCasting: The mostly teenage cast is played by actors in their 20s, making some casting choices downright bizarre. The actors who play the Gilberts are only one year apart, starting with Nina Dobrev (20), Steven R. Mc Queen (21), and [[PlayingGertrude Sarah Canning (22).]] And to top it off, [[Series/ADifferentWorld Whitley Gilbert]] (48) a grandma?!
** This is made extra weird by the casting of John Anders (born 1981) as [[spoiler: Elena's [[AbsurdlyYouthfulMother father]], John Gilbert.]] Isobel, who is supposed to be younger than him even without being a vampire, is played 35-year-old Mia Kirshner.
** Justified in the case of Jasmine Guy as "Grams" Sheila Bennett; she's meant to have preternatural longevity as a witch. Stefan mentions first meeting her at a protest rally in the 60s, though he's not sure she would remember. She did.
* FakeAmerican:
** Elena is played by Bulgarian-born Canadian Nina Dobrev
** Several of the originals (at least Klaus, Rebekah, and Kol plus the dead son Henrick) were born in the New World, making them and are not played by American actors
** American Hayley Marshall is played by Australian actress Phoebe Tonkin.
* FakeNationality:
** Hispanic Michael Trevino plays the white Tyler Lockwood who is descended from Native Americans.
** The Salvatores are Italian-American, neither Paul Wesley nor Ian Somerhalder are Italian, neither does James Remar who plays their father.
* McLeaned: [[spoiler:Alaric]] was killed shortly before it was announced that CW would pick up a new show starring his actor.
* RomanceOnTheSet:
** Ian Somerhalder and Nina Dobrev.
** Candice Accola and Steven Mcqueen also dated but their characters were never really involved with each other.
** Paul Wesley's wife Torrey Devitto plays Meredith Fell.
* WhatCouldHaveBeen:
** Originally, the 4th-season-spanning [[spoiler: cure]] storyline was supposed to resolve with [[spoiler: Damon being the one to receive the cure]]. However, almost immediately after introducing [[spoiler: the cure]] as an idea, the writers were dismayed to find that a large number of fans were predicting that very outcome. So they changed mid-course, and [[spoiler: the cure was instead given to Katherine.]]
** A deleted scene reveals Kelly Donovan, Matt's mother, as a succubus.

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