!!The movie:
* ActingForTwo: In the flashback, the medieval Slayer and her Watcher are played by the same actors as Buffy and Merrick. On the other hand, the Slayer and the Watcher continually reincarnate looking identical to her past lives, so they are theoretically still the same characters.
* CastingGag: The BigBad of the movie was a vampire played by Creator/RutgerHauer. Creator/AnneRice had originally envisioned Hauer as Lestat when she wrote ''Literature/TheVampireChronicles'', but by the time ''Film/InterviewWithAVampire'' was filmed in the early 90s, she said he was too old to play Lestat.
* DawsonCasting: 22-year-old Creator/KristySwanson playing high school senior Buffy.
* FakeNationality: The medieval maiden played by the California-born Swanson in the flashback sequences would obviously have to be non-American. She comes off as [[FakeBrit English]] [[NotEvenBotheringWithTheAccent (not that Swanson tries very hard)]], but a brief line by Merrick suggests that she was Hungarian. (In the original script, she's an Italian.)
* FakeBrit: Merrick, a British character being played by the Canadian Creator/DonaldSutherland.
* ThrowItIn: Amilyn's ludicrously protracted and over-the-top death in the movie, ad-libbed by Paul Reubens.
* ThePeteBest: Swanson. Then again this was 1992 and it would be five years till the TV series, long after Swanson grew out of the role.
* WagTheDirector: According to Creator/JossWhedon, Creator/DonaldSutherland was under the impression that he was the star of the film. And rewrote all of his dialogue.
* WhatCouldHaveBeen: Creator/AlyssaMilano almost got the lead role in the original movie.
** The first incarnation of Creator/JossWhedon's idea of "a young woman who is far more than she seems" that eventually developed into ''Buffy'' was called "Rhonda the Immortal Waitress".

!!The TV series:
* AbilityOverAppearance:
** Producers were reluctant to cast Creator/AmberBenson as Tara because she was too voluptuous for the supposedly plain girl, but she won them over with her awkwardness.
** Creator/AlysonHannigan's casting went something like this too. Joss stated that all the other girls who auditioned for Willow wore NerdGlasses and acted stereotypically [[HollywoodNerd nerdy]]. Alyson won the part based on the fact that she didn't do that.
* ActorAllusion: Giles piping in "Dance Macabre" during his slideshow presentation in "[[{{Recap/BuffyTheVampireSlayerS4E10Hush}} Hush]]". Creator/AnthonyStewartHead appeared in the pilot of ''Series/JonathanCreek'', which used this song as its theme.
* ActorSharedBackground:
** Creator/JamesMarsters based his accent on Anthony Stewart Head's. Giles uses an RP English accent on-camera, but his actor sounds like a working-class "tough guy" in real life, using an accent close to Estuary English. Head uses it for Giles' adolescent persona in "Band Candy."
** In "Nightmares", Buffy's personal nightmare is being buried alive by the Master. Creator/SarahMichelleGellar is terrified of graveyards for this same reason, which is [[NightmareFuel amusing]] seeing as her character was buried alive ''twice'' in the show ("Nightmares" and "Bargaining Pt. 1"), and [[IronicFear spends most of her evenings in graveyards]].
** Creator/AlysonHannigan maintains that she [[PerformanceAnxiety cannot sing or dance]] (which hasn't stopped multiple writers from shoehorning her into [[Series/HowIMetYourMother splashy musical numbers]], but oh well), mirroring Willow's nightmare of being forced to sing ''MadameButterfly''. ("[[{{Recap/BuffyTheVampireSlayerS1E10Nightmares}} Nightmares]]")
** Baby Buffy went through a phase during which she idolized ice skater Dorothy Hamill. Gellar enjoys figure skating in real life, a skill which was put to good use in "What's My Line Pt 1".
** The scene in "[[Recap/BuffyTheVampireSlayerS3E8LoversWalk Lovers Walk]]" where Cordelia gets impaled is based on a real incident. At five years old, playing around a swimming pool that was still under construction, Creator/CharismaCarpenter fell onto a piece of rebar. Only in real life she fell off a horse and not through stairs.
** Faith became a Boston native after Creator/ElizaDushku was cast, though Eliza herself is actually from Watertown rather than South Boston like Faith.
* BreakthroughHit: For Creator/JossWhedon.
* CreatorBacklash:
** Creator/SarahMichelleGellar disliked Season 6 because of the dark tone of the storylines. She also wasn't a fan of the extensive preparation that had to be done for the MusicalEpisode.
** Most of the cast came to hate the library scenes because they would take forever to film.
** Creator/JamesMarsters was so disturbed by Spike's attempted rape of Buffy that he had it written into his contract that he would never film such scenes again.
** Creator/SethGreen disliked being OutOfFocus in Season 3, as he hated having to show up for work when he'd only have one or two lines the whole time. This is why Oz gets PutOnABus midway through Season 4.
* CreatorsFavorite: Xander (who was a stand in for Joss), Dawn (with her actress being such a big fan of the series, focus was given to her), and Kennedy (Whedon really liked the character and gave a lot of focus to her) being standouts.
* TheDanza: Larry Bagby III as Larry Blaisdell. DB Woodside as Robin Wood.
* DawsonCasting:
** Some actors were a full decade older than their characters. In an extreme example, Creator/CharismaCarpenter was 26 when she played 16-year-old Cordelia.
** Averted by Dawn and Faith, who are both the same age as the actresses playing them (Creator/ElizaDushku was even legally emancipated from her parents so she wouldn't be limited by child labor laws).
* FakeBrit:
** Spike, played by American Creator/JamesMarsters.
** Wesley, played by Seattle native Alexis Denisof.
* FakeIrish: Boreanaz's accent leaves much to be desired.
* {{Fanon}}: Many fanfics paint the idea that Dawn is actually the daughter of Spike and Buffy, the monks using DNA from both.
* HeAlsoDid: Nicholas Brendon (the guy who played Xander) [[http://verybadkoalas.com/2010/09/29/episode-1/ has a webcomic]].
* HeyItsThatPlace: The external (and some internal) shots of Sunnydale High School are of Torrance High, the same school used for the ''Series/BeverlyHills90210''
** The exterior of Angel's mansion is of Frank Lloyd Wright's Ennis House, a popular shooting location.
** Buffy's old school, Hemery High, is the clock tower made famous in ''Film/BackToTheFuture''.
** "Fear Itself" took place in what would become better known as the Murder House house in ''Series/AmericanHorrorStoryMurderHouse''.
** The battle between the Slayers and Kakistos ("Faith, Hope, and Trick") takes place inside L.A. Firestation 23, also used as HQ for the ''Franchise/{{Ghostbusters}}.''
** The Gentlemen are seen floating down the same street that later served as [[DesperateHousewives Wisteria Lane.]]
* NamesTheSame:
** Everyone knows Cordelia. Cheerleader. AlphaBitch. Rival of Buffy. Hopeless with rifles. There's also [[LollipopChainsaw Cordelia.]] Her little sister is a cheerleader. {{Tomboy}}. Very much an ally. Wields a sniper rifle.
** Definitely a coincidence, but still funny: in the comic ComicBook/{{WITCH}}, there's a redheaded MagicalGirlWarrior called ''Will'' who has a bit of LesYay with a shy MagicalGirlWarrior called Tara''nee''. The same comic also features a LovableAlphaBitch called Cor''n''elia.
* NamesToRunAwayFromReallyFast: Real life example: Robia [=LaMorte=]'s (miss Calendar) surname means "(the) death" in Italian and "the dead woman" in French.
* TheOtherDarrin: Nikki Wood, the second slayer Spike kills, is played by a stuntwoman in "Fool For Love." When The First assumes her shape in Season 7, she was recast as a more vulnerable-looking actress.
** Buffy's old mentor Merrick looks different in a season 2 flashback.
* TheOtherMarty: Riff Regan played Willow in the unaired Proof of Concept to sell the show but never intended to play her in the series.
* PlayingAgainstType: So Creator/SethGreen isn't the PluckyComicRelief?
* PromotedFangirl:
** Michelle Trachtenberg was a huge fan of ''Buffy'' before being signed onto the show, and once told Joss "There was never a Buffy episode that sucked. I love you!"
** When "[[Recap/BuffyTheVampireSlayerS3E8LoversWalk Lover's Walk]] episode originally aired in the US, it was followed by an advert for the phone service 1800-COLLECT, in which Creator/SarahMichelleGellar and Creator/DavidBoreanaz offered a prize of a walk-on part in "[[Recap/BuffyTheVampireSlayerS3E20TheProm The Prom]]."
* RealLifeRelative: Nick Brendon's twin brother worked as his stunt double, and they also brought him in to play Xander's magically created double in season five's "[[{{Recap/BuffyTheVampireSlayerS5E3TheReplacement}} The Replacement]]".
* RecycledTheSeries: Although not so much recycled as "remade properly" according to Creator/JossWhedon's vision.
* RomanceOnTheSet:
** Here's an odd one: Amber Benson and Adam Busch... who played Tara and Warren respectively.
** Creator/AlysonHannigan (Willow) is married to Alexis Denisof (Wesley).
* ThrowItIn:
** The famous Creator/MutantEnemy title card was reportedly scribbled by Whedon with only seconds to go until broadcast.
** In "[[Recap/BuffyTheVampireSlayerS2E14Innocence Innocence]]", The scene where Angel dumps Buffy in his apartment was originally supposed to take place on Buffy's lawn. Halfway through shooting the scene, SMG and David Boreanaz told Joss that the scene wasn't working, so he moved it to the bedroom. Buffy can still heard saying she saw him "at the house". She was so LostInCharacter afterwards they had to close down the set for half an hour, being that invested in the romance.
** The gag in "[[Recap/BuffyTheVampireSlayerS3E18Earshot Earshot]]" with Giles walking into a tree was ad-libbed by Creator/AnthonyStewartHead. He never dreamed Joss would keep in the cut.
** In the [[Recap/BuffyTheVampireSlayerS3E22GraduationDayPart2 Season Three finale]], Cordelia [[SecurityCling cowers behind]] the diminutive Jonathan. According to Danny Strong, this scene was an idea of Charisma's, because she was leaving for ''Angel'' and never got much screen time with him.
* TooSoon: The episode "Earshot", which depicts a student bringing a rifle to school [[spoiler: (albeit to kill himself and no one else)]], was set to air within a week of Columbine and was therefore delayed until after the season finale, which was also delayed in light of Columbine because of [[spoiler: the destruction of Sunnydale High School.]]
* ThrowItIn: Not in the original work but in the motion comic ''Anywhere But Here'' there is a scene where Kennedy guesses Willow is upset about Tara's death. A line's added that makes her look like Queen Bitch.
* TropeNamer: For...
** BigBad: And, by extension, its {{snowclones}}:
*** BigBadDuumvirate: The Trio.
*** BigBadEnsemble
*** BigBadWannabe: Poor Spike fits the bill. And he's the trope namer for "Big Bad", too! Life is so unfair.
*** BigGood: This being a Whedon show, though, even the Big Goods (Quentin Travers, Sineya, the Shadow Men) [[KnightTemplar aren't very good]].
** BreakawayPopHit[[invoked]]: "Once More With Feeling"
** BuffySpeak
** ButtMonkey: Xander used it to refer to himself in "Buffy vs. Dracula."
** CameBackWrong: "Smashed"
** CameBackStrong: "Prophecy Girl"
** FunnyAneurysmMoment: "The Freshman" (InUniverse version)[[invoked]]
** GameFace: "Prophecy Girl"
** InferioritySuperiorityComplex: Holden Webster's expert opinion on Buffy. ("Conversations with Dead People")
** InsaneTrollLogic: "Triangle"
** UseYourHead: Spike's [[BadBoss helpful suggestion]] to one of his mooks ("[[Recap/BuffyTheVampireSlayerS2E3SchoolHard School Hard]]")
* And the ''[[Administrivia/RenamedTropes former]]'' Trope Namer for:
** BadassDecay: Formerly known as Spikeification.[[invoked]]
** ChekhovsBoomerang: Formerly known as Olaf's Hammer.
** FangThpeak: Formerly known as WhedonThyndrome.
** WeirdnessCensor: Formerly known as SunnydaleSyndrome.
* WhatCouldHaveBeen:
** At the height of its popularity, a animated version was considered. They had got the designs down and even made a promo. But no network was willing to buy it and it wound up dropped in the end. Though it did get a nod in the season 8 comic which somewhat lampshades the missed opportunity.
** Creator/JossWhedon planned to make a spin-off called "Ripper", about Giles' adventures in England. At first it was meant to be a show, then a mini-series, then finally a made-for-TV movie. Apparently, he still hopes to make it.
** After the series ended, Creator/ElizaDushku was offered her own spin-off series as the character Faith. But then she turned it down to do ''Tru Calling''.
** Amongst those who auditioned for Buffy were Creator/KatieHolmes and Creator/SelmaBlair.
** Creator/RyanReynolds was originally offered the role of Xander. He passed on it because of his own awful high school experiences. "I love that show and I loved Creator/JossWhedon," Reynolds told 'The Toronto Star' in 2008. "But my biggest concern was that I didn't want to play a guy in high school."
** Creator/NathanFillon auditioned for Angel. He played Caleb in the last season.
** Dawn was originally intended to have the power to speak to the dead. She was also supposed to be able to move objects with her mind. These powers were later dropped.
** Originally, Whedon didn't want either of Buffy's parents to appear as characters on the show. Accepting that that could get complicated, he settled on just having her mother, Joyce, appear in a nearly regular role, while Buffy's father Hank appeared in very few episodes.
** Oz was originally supposed to wear thick rimmed glasses, much like the lead singer of Music/{{Weezer}}. This was dropped at the last minute as Whedon felt that it looked tacky.
** Whedon toyed with the idea of making Xander gay instead of Willow.
** Spike, Oz, Faith, Wesley and Drusilla were all supposed to be killed off, but have ended up living long past their initial storylines. Also, [[spoiler:Jenny and Joyce were supposed to be killed off sooner than they were]].
** The Oz-Veruca storyline in season four was supposed to last longer, but had to be cut short when Seth Green left the series.
** According to Nicholas Brendon, he and Creator/SarahMichelleGellar proposed a storyline for season seven where Xander and Buffy get together romantically. Their idea was shot down, and they continued with the Buffy-Spike relationship.
** The Master was originally supposed to have a beard and long hair before Mark Metcalf suggested the bald look as a homage to ''Film/{{Nosferatu}}''.
** Creator/JamesMarsters originally auditioned for Spike with a Texan accent. This was quickly jettisoned in favor of a London accent instead.
* YouLookFamiliar: Spice Williams plays the police instructor who tries to murder Buffy, Patrice, in "What's My Line?" She also appeared in "The Zeppo" as a member of the Sisterhood of Jhe, and later turned up on ''Angel'' as a convict hired to kill Faith in prison.
** Creator/JeffKober first appeared in season three episode "Helpless" as a vampire named Kralik. He appeared again during season six as warlock Rack.
** Brian Thompson portrays the vampire "Luke" in season 1, aswell as the demon called "The Judge" in season 2.
** Tom Lenk plays a vampire lackey to Harmony a few season before playing Tucker's brother (and a member of the Trio).

!!The comics:
* ScheduleSlip: the last ''Spike'' issue.
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