* HeyItsThatGuy:
** Anna is [[{{Unfabulous}} Geena Fabiano]].
*** Her mother is played by Creator/KellyHu.
** [[Series/{{Heroes}} Adam Monroe]] is Elena and Jeremy's uncle, [[spoiler: as well as Elena's birth father.]]
*** Another one for ''Series/{{Heroes}}'' fans: Noah Bennet is Caroline's dad.
*** Gretchen is the [[spoiler: first vampire to be sired to Damon]].
** [[Series/TheLWord Jenny Schecter]] is Alaric's wife and [[spoiler: Elena's birth mother.]]
** Bonnie's Grandma is [[Series/DeadLikeMe Roxy]].
** Rebekah is [[Series/H2OJustAddWater a mermaid]].
*** She's also [[PrettyLittleLiars Samara]].
*** And an [[HilariousInHindsight ironic twist]], Maya is Bonnie's ancestor, Emily.
*** Plus, Melissa's no longer dating a doctor, now that she is one.
** Sarah, [[spoiler: the girl Tyler kills]] is [[CoryInTheHouse Meena]].
*** Also, she's [[DesperateHousewives Ana Solis]].
*** Her best friend that Katherine kills is [[SuiteLifeOnDeck London Tipton's former roommate]].
** Caroline's mom is [[KyleXY Nicole Trager]].
** Sage is [[{{Smallville}} Tess Mercer]].
** Stefan was [[AmericanDreams JJ's friend]] and [[{{Fallen}} an angel]].
*** He was also Sage's [[spoiler:[[{{Smallville}} half-brother Lucas]]]], even though they never appeared on-screen together.
** [[Series/{{Degrassi}} Mia]] is now torn between vampires.
** So Tyler used to be friends with [[TheSecretCircle Faye Chamberlain]]?
** [[OneTreeHill Lucas's girlfriend Lindsay]] is a werewolf.
** GinaTorres is Bree.
** Bonnie's human father was a [[Series/{{Supernatural}} vampire on another show]].
** [[SeventhHeaven Simon Camden]] is Ray.
** [[Series/TheOC Julie Cooper]] is Matt and Vicki's mom.
** April used to be friends with [[TheNineLivesOfChloeKing Chloe King]].
** [[Series/{{Arrow}} Green Arrow]] is Brady.
** [[Film/LegallyBlonde Warner Huntington III]] is Alaric.
** [[WizardsOfWaverlyPlace Stevie Nichols]] is Megan
*** She's also [[LemonadeMouth Stella]] and Ray is Luke.
** In a humorous example Nina Dobrev and Dillon Casey (who played Noah), both once played the romantic leads in a LifetimeMovieOfTheWeek
** [[TheLeague Shiva Kamini Soma Kandarkram!]]... is Qetsiyah.
** Aaron used to be [[LifeUnexpected Lux's teacher]]
** Damon and Series/{{Dexter}} have the same dad...that makes perfect sense.
* HeyItsThatVoice: Jason Spisak ([[VideoGame/FalloutNewVegas Vulpes Inculta]], [[WesternAnimation/YoungJustice Kid Flash]], [[WesternAnimation/GreenLanternTheAnimatedSeries Razer]]) provides the voice of Silas.
* IKnewIt: Show of hands: how many of you called [[spoiler: Stefan having killed his father?]] [[TheUntwist Yeah, thought so...]]
** Also in "The Departed" who guessed [[spoiler: the only way to kill Alaric would be to kill Elena and turn her into a vampire.]]
** Is there anyone who actually thought [[spoiler: Jeremy was going to come out of the hunter storyline alive?]]
** Many people guessed the third sacrifice would have consist of twelves witches.
** Also many people predicted Silas's lover would like [[spoiler: Elena]]
* 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.]]
* Devon Allowitz, who played Henrik Mikaelson, is the son of crew member Michael Allowitz