History WhatCouldHaveBeen / Arrowverse

* Creator/StephanieBeatriz campaigned to take over the lead for season 2 following Ruby Rose's departure. She'd be casted to voice Batwoman in ''Catwoman: Hunted''.

* Mr. Blank, a VillainOfTheWeek played by Creator/JAugustRichards, was originally supposed to be the DC Comics villain Onomatopoeia. However, as Onomatopoeia only speaks in, well, [[ExactlyWhatItSaysOnTheTin onomatopoeia]], they couldn't make it work without him coming across as mentally disabled (since sound effects sound far different in real life compared to comic books).

* A two-fer with the move to Canada for filming. If they hadn't moved, then Cat Grant would have probably stayed on through Season 2 (Creator/CalistaFlockhart nigh-exclusively shooting in LA), but they probably wouldn't have got Creator/KatieMcGrath as Lena Luthor (as an Irish citizen, it would be a lot harder to be able to work in the US for a long-term project with an unknown end date like a TV show is.)

* Creator/KeiynanLonsdale originally auditioned to play Jefferson Jackson (the Arrowverse' version of the second host body of ComicBook/{{Firestorm}}) for ''Series/LegendsOfTomorrow'' before the showrunners decided to cast him as ComicBook/WallyWest instead.

* The creators originally wanted to have Creator/RobbieAmell reprise his role from ''The Flash'' as ComicBook/{{Firestorm}}, but Amell couldn't commit. They ended up killing the character off on ''The Flash'' so they could have a new Firestorm to use in ''Legends of Tomorrow'' (choosing minor comic character Jax Jackson for that part).

** Creator/StephanieBeatriz campaigned to take over the lead from season 2 following Ruby Rose's departure. She'd be casted to voice Batwoman in ''Catwoman: Hunted''.

* Creator/BlakeLively, Creator/MinkaKelly, Creator/HilarieBurton, Creator/KatherineIsabelle, Creator/RachaelTaylor, Creator/AlexandraBreckenridge, Creator/MaggieGrace, Creator/BrittanySnow, and Creator/ShantelVanSanten were considered for the part of [[ComicBook/{{Black Canary}} Laurel Lance]] before the casting of Creator/KatieCassidy. [=VanSanten=] would eventually play Patty Spivot in ''The Flash'' Season 2, while Kelly would eventually play [[ComicBook/HawkAndDove a different bird-themed superheroine]] in ''Series/Titans2018'' who even made cameo at the end of ''Series/CrisisOnInfiniteEarths2019''.

* Mr. Blank was originally supposed to be the DC Comics villain Onomatopoeia. However, as Onomatopoeia only speaks in, well, [[ExactlyWhatItSaysOnTheTin onomatopoeia]], they couldn't make it work without him coming across as mentally disabled (since sound effects sound far different in real life compared to comic books).

* It was intended for the seventh major CrisisCrossover of the Arrowverse to be a joint with ''Batwoman'' and ''Series/SupermanAndLois''. Sadly whatever plans they might have had for this crossover were scrapped due to a combination of Ruby Rose leaving the show and the COVID-19 Pandemic making it unsafe to film large groups of people, and the entire crossover was abandoned in favor of a CrossThrough with former ''Arrow'' star Creator/DavidRamsey returning.

* After Andrew Kreisberg was fired, the majority of the second half of Season 3 had to be heavily rewritten. A lot of what was originally planned can be worked out by comments before the season. These include, word of God confirmation from Kreisberg himself that Lena would have turned evil by the end of the season by doing one small bad thing at a time; the casting for Sam and Ruby stated that the former was a one season fractional regular and the latter was recurring with an option to be a regular in season 4. It doesn't take much to work out that Sam was supposed to die and Alex would end up adopting Ruby; the shared nightmare that Kara and Sam had about Alura turning into a monster was never explained. With Creator/EricaDurramce signed for a certain amount of episodes and the Argo story coming out of nowhere, it seems likely that Alura would have been revealed as the creator of the Worldkillers (it was Jor-El in the comics) and Kara might have well have been one as well. Lena eventually did have a FaceHeelTurn in season 5, but in a different way than originally planned, the anger towards learning Kara was Supergirl made her become a WellIntentionedExtremist, and she eventually has a HeelFaceTurn near the end of that same season when they make amends.

* After Andrew Kreisberg was fired, the majority of the second half of Season 3 had to be heavily rewritten. A lot of what was originally planned can be worked out by comments before the season. These include, word of God confirmation from Kreisberg himself that Lena would have turned evil by the end of the season by doing one small bad thing at a time; the casting for Sam and Ruby stated that the former was a one season fractional regular and the latter was recurring with an option to be a regular in season 4. It doesn't take much to work out that Sam was supposed to die and Alex would end up adopting Ruby; the shared nightmare that Kara and Sam had about Alura turning into a monster was never explained. With Creator/EricaDurramce signed for a certain amount of episodes and the Argo story coming out of nowhere, it seems likely that Alura would have been revealed as the creator of the Worldkillers (it was Jor-El in the comics) and Kara might have well have been one as well. Lena eventually did have a FaceHeelTurn in season 5, but in a different way than originally planned, the anger towards learning Kara was Supergirl made her become a WellIntentionedExtemist, and she eventually has a HeelFaceTurn near the end of that same season when they make amends.

** Natasha Negovanlis, who plays the title role of ''WebVideo/CarmillaTheSeries'', auditioned for the role of [[ComicBook/{{Batwoman}} Kate Kane]].
** WordOfGod says the pilot contained a scene of the Kane family attending the bat mitzvah for the twins that was cut for time.
** [[spoiler:Former ''Series/{{Arrow}}'' and ''Series/LegendsOfTomorrow'' showrunner Marc Guggenheim wanted Creator/JensenAckles to play the Series/{{Arrowverse}} version of [[Franchise/{{Batman}} Bruce Wayne]] before Warren Christie was cast. Ackles would eventually get to voice Batman for ''WesternAnimation/BatmanTheLongHalloween''.]]

* Creator/KeiynanLonsdale originally auditioned to play Jefferson Jackson (the Arrowverse' version of the second host body of ComicBook/{{Firestorm}}) for ''Series/LegendsOfTomorrow'' before the showrunners decided to cast him as ComicBook/WallyWest Wally West instead.

** The same pilot also originally featured Kyle Nimbus/The Mist as the villain instead of Clyde Mardon, and he (not Ronnie Raymond) would have been the boyfriend/fiance of Caitlin Snow. For her part, Caitlin was originally envisioned as an older scientist (compared to the trio of Barry/Cisco/Hartley) and may have been intended to have a romantic arc with "Harrison Wells"; if true, this probably makes her Season Two romantic arc a case of RecycledScript.

* After Andrew Kreisberg was fired, the majority of the second half of Season 3 had to be heavily rewritten. A lot of what was originally planned can be worked out by comments before the season. These include, word of God confirmation from Kreisberg himself that Lena would have turned evil by the end of the season by doing one small bad thing at a time; the casting for Sam and Ruby stated that the former was a one season fractional regular and the latter was recurring with an option to be a regular in season 4. It doesn't take much to work out that Sam was supposed to die and Alex would end up adopting Ruby; the shared nightmare that Kara and Sam had about Alura turning into a monster was never explained. With Creator/EricaDurramce signed for a certain amount of episodes and the Argo story coming out of nowhere, it seems likely that Alura would have been revealed as the creator of the Worldkillers (it was Jor-El in the comics) and Kara might have well have been one as well.

* The creators originally wanted to have Creator/RobbieAmell reprise his role from ''The Flash'' as ComicBook/{{Firestorm}}, but Amell couldn't commit. They ended up killing the character off on ''The Flash'' so they could have a new Firestorm to use in ''Legends of Tomorrow''.
* Joseph David-Jones [[https://www.radiotimes.com/news/tv/2019-10-14/arrow-connor-hawke-legends-of-tomorrow/ revealed]] his character of Connor Hawke was originally supposed to become a series regular and join the Legends, but due to a combination of being unable to fit him in and the tone of the show changing to DenserAndWackier they scrapped the idea. He would later join the main cast of ''Series/{{Arrow}}'' in its last season.

* Likewise, the creators wanted Creator/MegalynEchikunwoke to reprise her role as Comicbook/{{Vixen}} from ''Arrow'' and her [[WesternAnimation/{{Vixen}} animated series]], but this was scrapped because of scheduling issues. The new Vixen in Season 2 was created as a replacement.

** [[spoiler:Former ''Series/{{Arrow}}'' and ''Series/LegendsOfTomorrow'' showrunner Marc Guggenheim wanted Creator/JensenAckles to play the Series/{{Arrowverse}} version of [[Franchise/{{Batman}} Bruce Wayne]] before Warren Christie was cast.]]

* Creator/KatieCassidy was suppose to show up in some capacity, but then [[Creator/DavidCassidy her father]] died so her planned appearance was written out so she could go to his funeral. ''The Flash'' episode, [[Recap/TheFlash2014S4E19FuryRogue "Fury Rogue"]] revealed she would've been cast as Siren X, the New Reichsmen's answer to the Black Canary, was Oliver-X's ex-lover and ''pissed'' that the Earth-1 heroes killed him.

* Creator/ClaireHolt was the runner-up for the role of [[Comicbook/{{Supergirl}} Kara Danvers]] before Creator/MelissaBenoist was cast. Other actresses who screen-tested for the part were [[Series/{{Hollyoaks}} Gemma Atkinson]], [[Series/OnceUponATime Elizabeth Lail]], and [[Film/{{Aquamarine}} Sara Paxton]].

** Former Black Canaries Alaina Huffman (''Series/{{Smallville}}'') and Creator/RachelSkarsten (''Series/BirdsOfPrey2002'') were also considered to reprise their roles as Laurel Lance for the series. Skarsten would eventually play Beth Kane / Alice in ''Series/Batwoman2019''.

* Creator/LaurenCohan was the first choice for [[ComicBook/{{Huntress}} Helena Bertinelli]], but turned down the offer due to scheduling commitments to ''Series/TheWalkingDead''. Janet Montgomery, Creator/ShelleyHennig, Creator/JessicaSzohr, and Anna Skellern were considered for the part as well before Jessica De Gouw was cast.

** Former Black Canaries Alaina Huffman (''Series/{{Smallville}}'') and Creator/RachelSkarsten (''Series/BirdsOfPrey'') were also considered to reprise their roles as Laurel Lance for the series. Skarsten would eventually play Beth Kane / Alice in ''Series/Batwoman2019''.
* Creator/LaurenCohan was the first choice for [[Comicbook/{{Huntress}} Helena Bertinelli]], but turned down the offer due to scheduling commitments to ''Series/TheWalkingDead''. Janet Montgomery, Creator/ShelleyHennig, Creator/JessicaSzohr, and Anna Skellern were considered for the part as well before Jessica De Gouw was cast.

[[caption-width-right:350:Concept art for [[Series/TheFlash2014 The Flash's]] suit]]

* Creator/BlakeLively, Creator/MinkaKelly, Creator/HilarieBurton, Creator/KatherineIsabelle, Creator/RachaelTaylor, Creator/AlexandraBreckenridge, Creator/MaggieGrace, Creator/BrittanySnow, and Creator/ShantelVanSanten were considered for the part of [[ComicBook/{{Black Canary}} Laurel Lance]] before the casting of Creator/KatieCassidy.
* Creator/LaurenCohan was the first choice for [[Comicbook/{{Huntress}} Helena Bertinelli]], but turned down the offer due to scheduling commitments to ''Series/TheWalkingDead''. Creator/ShelleyHennig was also considered for the part.

* The twentieth episode of Season Two was originally going to be a BackDoorPilot for a potential spin-off focusing on Franchise/TheFlash. Based on both the strength of Creator/GrantGustin's portrayal of Barry Allen in "[[Recap/ArrowS2E8TheScientist The Scientist]]" and "[[Recap/ArrowS2E9ThreeGhosts Three Ghosts]]" and the fact that using the twentieth episode as a BackDoorPilot would interrupt the show's momentum as it built up to the season finale, the decision was made to make it a standalone pilot.

* Season 3 Episode 5 is supposed to be titled "Oracle", but ComicBook/{{Batgirl}} was also ExiledFromContinuity, hence why it's titled "The Secret Origins of Felicity Smoak" instead.
* A.R.G.U.S. and the Suicide Squad were originally planned to be a major part of Season 3 but was scrapped by ExecutiveMeddling.
* Vigilante's identity was suppose to be revealed in Season 5, but due to time constraints and the production team unable to get the actor they wanted at the time, the Vigilante subplot was pushed to Season 6.

* Creator/MattBarr, Creator/JamesMackay, Creator/MikeKalinowski, and Creator/DavidAGregory screen-tested for the role of [[Comicbook/TheFlash Barry Allen]] before Creator/GrantGustin was cast.
* Creator/KeiynanLonsdale originally auditioned to play [[ComicBook/{{Firestorm}} Jefferson Jackson]] for ''Series/LegendsOfTomorrow'' before the showrunners decided to cast him as [[ComicBook/WallyWest Wally West]] instead.

* The writers considered using other romances to stall the fated Barry/Iris one - with a Barry/Caitlin romance being floated - but Grant Gustin insisted that Barry/Iris should happen sooner rather than later. This explains why Season 1 had so many scenes suggesting a possible romantic attraction between Barry and Caitlin, and why it ended after Season 2.

* Creator/ClaireHolt was the runner-up for the role of [[Comicbook/{{Supergirl}} Kara Danvers]] before Creator/MelissaBenoist was cast.

* Creator/BrentSpiner was originally cast as President Baker in Season 4 but had a scheduling conflict, and was replaced with Bruce Boxleitner, incidentally creating a quite fun irony with his role in ''Series/BabylonFive''.
* A two-fer with the move to Canada for filming. If they hadn't moved, then Cat Grant would have probably stayed on through season 2 (Calista Flockhart nigh-exclusively shooting in LA), but they probably wouldn't have got Creator/KatieMcGrath as Lena Luthor (as an Irish citizen, it would be a lot harder to be able to work in the US for a long-term project with an unknown end date like a TV show is.)

* The team was going to be named the [[ComicBook/JusticeSocietyOfAmerica Justice Society]], but Creator/GeoffJohns nixed it so the real JSA could be saved for any future appearances.
* The creators originally wanted to have Creator/RobbieAmell reprise his role from ''The Flash'' as Firestorm, but Amell couldn't commit. They ended up killing the character off on ''The Flash'' so they could have a new Firestorm to use in ''Legends of Tomorrow''.

* The show originally planned on tackling Ra's Al-Ghul and Damien Darhk's [[WeUSedToBeFriends friendship and fallout]] but was scrapped for unknown reasons.

* The plan for season 4 was that Nate's father, Hank Heywood, would be the season's BigBad. The team would discover Hank was running a secret government plot that would use magical creatures as super-soldiers. This would involve Nate, desperate to finally get his father's approval, make a FaceHeelTurn on the team. However, the showrunners loved Creator/ThomasFWilson's performance as Hank so much (as well as the great way Hank and Nate bonded) that they couldn't go through with making him the bad guy. Instead, they reworked the plans for Hank being an unknown puppet for demon Neron.

* In early drafts of Season Two, [[spoiler:Sara was originally going to take the role of Ravager, but eventually ended up as the [[ComicBook/BlackCanary Canary]]. Instead, the role of Ravager was given to Isabel Rochev]].

* The character who was going to buy out Queen Consolidated was originally going to be [[ComicBook/BlueBeetle Ted Kord]], a character whose existence was already implied through the appearance of Kord Industries. However, DC enacted an embargo on him due to "other plans", so the creators instead went with [[ComicBook/TheAtom Ray Palmer]]. This means that [[spoiler:the A.T.O.M. suit functions more like the Blue Beetle or Iron Man suits than it does its comic counterpart]]. This received an amusing DevelopmentGag the following season, when the team needs to steal a piece of tech from Kord’s company to bring Ray back to normal size.

* [[spoiler: Malcolm was originally considered to be Oliver's actual father. The showrunners ultimately decided against it since it's too [[Franchise/StarWars "Darth Vader and Luke"]] so they gave the StoryArc to Thea instead. Still, this was given a DiscontinuityNod in the Season 3 finale when Malcolm tells Oliver that he always viewed him "as a son".]]

* Creator/JustinHartley, ''Series/{{Smallville}}''[='s=] Green Arrow, was considered to [[Main/RoleReprisal reprise his role]] back when the show was still being pitched. The higher-ups then decided that his rendition won't fit the DarkerAndEdgier tone of the series and amicably parted ways.

* [[http://www.digitalspy.com/tv/the-flash/news/a862548/the-flash-danielle-panabaker-refused-caitlin-ralph-romance/ Early on in the series]], Hartley Sawyer revealed that the writers originally wanted to pair Ralph and Caitlin, [[LampshadeHanging pointing out that "Caitlin gets with the new white guy on the show every year"]], but Danielle Panabaker fought against it. Additionally, the writers considered using other romances to stall the fated Barry/Iris one - with a Barry/Caitlin romance being floated - but Grant Gustin insisted that Barry/Iris should happen sooner rather than later.

* Creator/LiamMcIntyre was reportedly the runner-up for the role of [[ComicBook/GreenArrow Oliver Queen]] had Creator/StephenAmell not been cast. [=McIntyre=] would later go on to portray Weather Wizard in ''Series/TheFlash2014''.
** Creator/JustinHartley, ''Series/{{Smallville}}''[='s=] Green Arrow, was considered to [[Main/RoleReprisal reprise his role]] back when the show was still being pitched. The higher-ups then decided that his rendition won't fit the DarkerAndEdgier tone of the series and amicably parted ways.
* Creator/BlakeLively, Creator/MinkaKelly, Creator/HilarieBurton, Creator/KatherineIsabelle, Creator/RachaelTaylor, Creator/AlexandraBreckenridge, Creator/MaggieGrace, Creator/BrittanySnow, and Creator/ShantelVanSanten were considered for the part of [[ComicBook/{{Black Canary}} Laurel Lance]] before the casting of Creator/KatieCassidy. [=VanSanten=] would eventually go on to play Patty Spivot on ''Series/TheFlash2014'' during its second season.
** Former Black Canaries [[Series/{{Smallville}} Alaina Huffman]] and Creator/RachelSkarsten were also considered to reprise their roles as Laurel Lance for the series. Skarsten was eventually cast as Red Alice in ''Series/{{Batwoman 2019}}''.
* Creator/LaurenCohan was the first choice for [[Comicbook/{{Huntress}} Helena Bertinelli]], but turned down the offer due to scheduling commitments to ''Series/TheWalkingDead'' .
** [[Series/NewAmsterdam2018 Janet Montgomery]], Creator/ShelleyHennig, [[Literature/GossipGirl Jessica Szohr]], and [[Film/TheDescentPart2 Anna Skellern]] were considered for the part of Huntress as well before [[Series/{{Dracula}} Jessica De Gouw]] was cast.

** [[Series/{{Smash}} Andy Mietnus]] also auditioned for the part of The Flash before the casting of Gustin. Mietnus would eventually go on to portray Hartley Rathaway in ''[[Recap/TheFlash2014S1E11TheSoundAndTheFury The Sound and the Fury]].''

* Before she was cast as Patty Spivot, Creator/ShantelVanSanten was one of the actresses considered to play [[Comicbook/BlackCanary Laurel Lance]] on ''Series/{{Arrow}}'' when that show was still being conceptualized.
* Creator/RickCosnett was originally considered to portray ''Jay Garrick'', not Eddie Thawne.

** [[Series/{{Hollyoaks}} Gemma Atkinson]], [[Series/OnceUponATime Elizabeth Lail]], and [[Film/{{Aquamarine}} Sara Paxton]] screen-tested for the part of Supergirl as well before the casting of Benoist.

* Creator/KeiynanLonsdale originally auditioned for Jefferson Jackson, but the showrunners decided he's better suited to play Wally West on ''Series/TheFlash2014'' so he was cast as that instead.

* Creator/MattBarr, Creator/JamesMackay, Creator/MikeKalinowski, and Creator/DavidAGregory]] screen-tested for the role of [[Comicbook/TheFlash Barry Allen]] before Creator/GrantGustin was cast.

* [[Series/HatfieldsAndMcCoys Matt Barr]], [[Series/Dynasty2017 James Mackay]], [[Series/JaneTheVirgin Mike Kalinowski]], and [[Series/OneLifeToLive David A. Gregory]] screen-tested for the role of [[Comicbook/TheFlash Barry Allen]] before Creator/GrantGustin was cast.

* [[https://twitter.com/james_eagan/status/1072358719839748096 Other names]] for [[Recap/LegendsOfTomorrowS4E8LegendsOfToMeowMewow Legends Of To-Meow-Mewow]]

* Creator/MinkaKelly, [[Series/OneTreeHill Hilarie Burton]], Creator/KatherineIsabelle, Creator/RachaelTaylor, Creator/AlexandraBreckenridge, Creator/MaggieGrace, Creator/BrittanySnow, and Creator/ShantelVanSanten were considered for the part of [[ComicBook/{{Black Canary}} Laurel Lance]] before the casting of Creator/KatieCassidy. [=VanSanten=] would eventually go on to play Patty Spivot on ''Series/TheFlash2014'' during its second season.

* The twentieth episode of ''Series/{{Arrow}}'''s second season was originally going to be a BackDoorPilot for a potential spin-off focusing on Franchise/TheFlash. Based on both the strength of Grant Gustin's portrayal of Barry Allen in [[Recap/ArrowS2E8TheScientist "The Scientist"]] and [[Recap/ArrowS2E9ThreeGhosts "Three Ghosts"]] and the fact that using the twentieth episode as a BackDoorPilot would interrupt the show's momentum as it built up to the season finale, the decision was made to make it a standalone pilot.

* The plan for season 4 was that Nate's father, Hank Heywood, would be the season's BigBad. The team would discover Hank was running a secret government plot that would use magical creatures as super-soldiers. This would involve Nate, desperate to finally get his father's approval, make a FaceHeelTurn on the team. However, the showrunners loved Tom Wilson's performance as Hank so much (as well as the great way Hank and Nate bonded) that they couldn't go through with making him the bad guy. Instead, they reworked the plans for Hank being an unknown puppet for demon Neron.

* The plan for season 4 was that Nate's father, Hank Heywood, would be the season's BigBad. The team would discover Nate was running a secret government plot that would use magical creatures as super-soldiers. This would involve Nate, desperate to finally get his father's approval, make a FaceHeelTurn on the team. However, the showrunners loved Tom Wilson's performance as Hank so much (as well as the great way Hank and Nate bonded) that they couldn't go through with making him the bad guy. Instead, they reworked the plans for Hank being an unknown puppet for demon Neron.

** Creator/LiamMcIntyre was reportedly the runner-up for the role of [[ComicBook/GreenArrow Oliver Queen]] had Creator/StephenAmell not been cast. [=McIntyre=] would later go on to portray Weather Wizard in ''Series/TheFlash2014''.
*** Creator/JustinHartley, ''Series/{{Smallville}}''[='s=] Green Arrow, was considered to [[Main/RoleReprisal reprise his role]] back when the show was still being pitched. The higher-ups then decided that his rendition won't fit the DarkerAndEdgier tone of the series and amicably parted ways.
** Creator/MinkaKelly, [[Series/OneTreeHill Hilarie Burton]], Creator/KatherineIsabelle, Creator/RachaelTaylor, Creator/AlexandraBreckenridge, Creator/MaggieGrace, Creator/BrittanySnow, and Creator/ShantelVanSanten were considered for the part of [[ComicBook/{{Black Canary}} Laurel Lance]] before the casting of Creator/KatieCassidy. [=VanSanten=] would eventually go on to play Patty Spivot on ''Series/TheFlash2014'' during its second season.
*** Former Black Canaries [[Series/{{Smallville}} Alaina Huffman]] and Creator/RachelSkarsten were also considered to reprise their roles as Laurel Lance for the series. Skarsten was eventually cast as Red Alice in ''Series/{{Batwoman 2019}}''.
** Creator/LaurenCohan was the first choice for [[Comicbook/{{Huntress}} Helena Bertinelli]], but turned down the offer due to scheduling commitments to ''Series/TheWalkingDead'' .
*** [[Series/NewAmsterdam2018 Janet Montgomery]], Creator/ShelleyHennig, [[Literature/GossipGirl Jessica Szohr]], and [[Film/TheDescentPart2 Anna Skellern]] were considered for the part of Huntress as well before [[Series/{{Dracula}} Jessica De Gouw]] was cast.
** Before [[Film/{{Riddick}} Matt Nable]] was cast, Creator/LiamNeeson said he'd play the show's version of ComicBook/RasAlGhul "in a heartbeat". WordOfGod states that after learning this, the network approached Neeson on the off chance he had the time, but they were unable to reconcile their schedules.
** The character who was going to buy out Queen Consolidated was originally going to be [[ComicBook/BlueBeetle Ted Kord]], a character whose existence was already implied through the appearance of Kord Industries. However, DC enacted an embargo on him due to "other plans", so the creators instead went with [[ComicBook/TheAtom Ray Palmer]]. This means that [[spoiler:the A.T.O.M. suit functions more like the Blue Beetle or Iron Man suits than it does its comic counterpart]]. This received an amusing DevelopmentGag the following season, when the team needs to steal a piece of tech from Kord’s company to bring Ray back to normal size.
** There were plans to use ComicBook/HarleyQuinn past her initial unnamed cameo, but WB/DC put the kibosh on this after the ''Film/SuicideSquad2016'' movie was greenlit. Presumably this was due to the same reason shows like ''Series/{{Smallville}}'' and ''WesternAnimation/JusticeLeagueUnlimited'' were [[ExiledFromContinuity barred from using certain characters who were being highlighted in movies at the time]]. Creator/WillaHolland later commented on this, confirming that had Harley been allowed, she would have played a significant role in Season 4.
** Mr. Blank was originally supposed to be the DC Comics villain Onomatopoeia. However, as Onomatopoeia only speaks in, well, [[ExactlyWhatItSaysOnTheTin onomatopoeia]], they couldn't make it work without him coming across as mentally disabled (since sound effects sound far different in real life compared to comic books).
** Roy was going to return for a guest appearance in season five, but other commitments prevented Creator/ColtonHaynes to return, so his appearance in season five ended up being StockFootage of him for the CrisisCrossover "Invasion!". He eventually returned as a series regular for Season 7.
** [[spoiler: Malcolm was originally considered to be Oliver's actual father. The showrunners ultimately decided against it since it's too [[Franchise/StarWars "Darth Vader and Luke"]] so they gave the StoryArc to Thea instead. Still, this was given a DiscontinuityNod in the Season 3 finale when Malcolm tells Oliver that he always viewed him "as a son".]]
** The twentieth episode of Season Two was originally going to be a BackDoorPilot for a potential spin-off focusing on Franchise/TheFlash. Based on both the strength of Creator/GrantGustin's portrayal of Barry Allen in "[[Recap/ArrowS2E8TheScientist The Scientist]]" and "[[Recap/ArrowS2E9ThreeGhosts Three Ghosts]]" and the fact that using the twentieth episode as a BackDoorPilot would interrupt the show's momentum as it built up to the season finale, the decision was made to make it a standalone pilot.
** In early drafts of Season Two, [[spoiler:Sara was originally going to take the role of Ravager, but eventually ended up as the [[ComicBook/BlackCanary Canary]]. Instead, the role of Ravager was given to Isabel Rochev]].
** Season 3 Episode 5 is supposed to be titled "Oracle", but ComicBook/{{Batgirl}} was also ExiledFromContinuity, hence why it's titled "The Secret Origins of Felicity Smoak" instead.
** A.R.G.U.S. and the Suicide Squad were originally planned to be a major part of Season 3 but was scrapped by ExecutiveMeddling.
** Vigilante's identity was suppose to be revealed in Season 5, but due to time constraints and the production team unable to get the actor they wanted at the time, the Vigilante subplot was pushed to Season 6.
** The second half of Season 6 had to be heavily rewritten after they couldn't get Creator/MichaelEmerson to commit to a full season, turning his intended BigBad into a patsy for one of his supposed henchmen.

** [[Series/HatfieldsAndMcCoys Matt Barr]], [[Series/Dynasty2017 James Mackay]], [[Series/JaneTheVirgin Mike Kalinowski]], and [[Series/OneLifeToLive David A. Gregory]] screen-tested for the role of [[Comicbook/TheFlash Barry Allen]] before Creator/GrantGustin was cast.
*** [[Series/{{Smash}} Andy Mietnus]] also auditioned for the part of The Flash before the casting of Gustin. Mietnus would eventually go on to portray Hartley Rathaway in ''[[Recap/TheFlash2014S1E11TheSoundAndTheFury The Sound and the Fury]].''
** Creator/KeiynanLonsdale originally auditioned to play [[ComicBook/{{Firestorm}} Jefferson Jackson]] for ''Series/LegendsOfTomorrow'' before the showrunners decided to cast him as [[ComicBook/WallyWest Wally West]] instead.
** Before she was cast as Patty Spivot, Creator/ShantelVanSanten was one of the actresses considered to play [[Comicbook/BlackCanary Laurel Lance]] on ''Series/{{Arrow}}'' when that show was still being conceptualized.
** Creator/RickCosnett was originally considered to portray ''Jay Garrick'', not Eddie Thawne.
** Linda Park's initial appearance was intended to just be an EasterEgg for the fans, before the writers decided to bring her back in a recurring role.
** Mirror Master and Dr. Alchemy were supposed to show up in Season Two, but for one reason or another never did. They do however show up in Season Three.
** In the original script for the Pilot, Albert Desmond (one version of Doctor Alchemy in the comics) was featured in a flashback as a kid that Barry was protecting from bullies. This was cut from the aired version of the Pilot, but a version of Desmond did eventually appear in the form of Julian Albert.
** The twentieth episode of ''Series/{{Arrow}}'''s second season was originally going to be a BackDoorPilot for a potential spin-off focusing on Franchise/TheFlash. Based on both the strength of Grant Gustin's portrayal of Barry Allen in [[Recap/ArrowS2E8TheScientist "The Scientist"]] and [[Recap/ArrowS2E9ThreeGhosts "Three Ghosts"]] and the fact that using the twentieth episode as a BackDoorPilot would interrupt the show's momentum as it built up to the season finale, the decision was made to make it a standalone pilot.
** An early draft of the pilot revealed that Hartley Rathaway was initially going to still be part of S.T.A.R. Labs when Barry woke up and (presumably) a main character and member of Team Flash -- he would also have been the one to design the suit, with the "design for firefighters" aspect due to having dated a fireman in the past. Presumably, this was removed in order to give Cisco a more substantial role in the plot as well as to get a chance to portray Hartley as the Pied Piper without invoking a FaceHeelTurn.
*** The same pilot also originally featured Kyle Nimbus/The Mist as the villain instead of Clyde Mardon, and he (not Ronnie Raymond) would have been the boyfriend/fiance of Caitlin Snow. For her part, Caitlin was originally envisioned as an older scientist (compared to the trio of Barry/Cisco/Hartley) and may have been intended to have a romantic arc with "Harrison Wells"; if true, this probably makes her Season Two romantic arc a case of RecycledScript.
** [[http://www.digitalspy.com/tv/the-flash/news/a862548/the-flash-danielle-panabaker-refused-caitlin-ralph-romance/ Early on in the series]], Hartley Sawyer revealed that the writers originally wanted to pair Ralph and Caitlin, [[LampshadeHanging pointing out that "Caitlin gets with the new white guy on the show every year"]], but Danielle Panabaker fought against it. Additionally, the writers considered using other romances to stall the fated Barry/Iris one - with a Barry/Caitlin romance being floated - but Grant Gustin insisted that Barry/Iris should happen sooner rather than later.

** Creator/ClaireHolt was the runner-up for the role of [[Comicbook/{{Supergirl}} Kara Danvers]] before Creator/MelissaBenoist was cast.
*** [[Series/{{Hollyoaks}} Gemma Atkinson]], [[Series/OnceUponATime Elizabeth Lail]], and [[Film/{{Aquamarine}} Sara Paxton]] screen-tested for the part of Supergirl as well before the casting of Benoist.
** Creator/DavidHarewood was originally supposed to portray Hank Henshaw as an eventual villain. But while filming the pilot, the producers noted that he could have played the Comicbook/MartianManhunter, and Creator/GeoffJohns convinced the rest to rewrite their plans for his character. In the second season, he gets to play both.
** Creator/GregBerlanti actually wanted to have Creator/LauraVandervoort much earlier but she couldn't because of her commitment to ''Series/{{Bitten}}'' (she plays TheHero there). After shooting that series' GrandFinale, she was finally able to appear.
** Creator/BrentSpiner was originally cast as President Baker in Season 4 but had a scheduling conflict, and was replaced with Bruce Boxleitner, incidentally creating a quite fun irony with his role in ''Series/BabylonFive''.
** A two-fer with the move to Canada for filming. If they hadn't moved, then Cat Grant would have probably stayed on through season 2 (Calista Flockhart nigh-exclusively shooting in LA), but they probably wouldn't have got Creator/KatieMcGrath as Lena Luthor (as an Irish citizen, it would be a lot harder to be able to work in the US for a long-term project with an unknown end date like a TV show is.)

** The original idea for the third Series/{{Arrowverse}} show was to simply give ComicBook/TheAtom his own series. But Creator/TheCW execs got cold feet after his lukewarm reception during Season 3 of ''Arrow'', so it was heavily retooled to be about an entire team.
** The team was going to be named the [[ComicBook/JusticeSocietyOfAmerica Justice Society]], but Creator/GeoffJohns nixed it so the real JSA could be saved for any future appearances.
** Creator/KeiynanLonsdale originally auditioned for Jefferson Jackson, but the showrunners decided he's better suited to play Wally West on ''Series/TheFlash2014'' so he was cast as that instead.
** The creators originally wanted to have Creator/RobbieAmell reprise his role from ''The Flash'' as Firestorm, but Amell couldn't commit. They ended up killing the character off on ''The Flash'' so they could have a new Firestorm to use in ''Legends of Tomorrow''.
** Likewise, the creators wanted Creator/MegalynEchikunwoke to reprise her role as Comicbook/{{Vixen}} from ''Arrow'' and her [[WesternAnimation/{{Vixen}} animated series]], but this was scrapped because of scheduling issues. The new Vixen in Season 2 was created as a replacement.
*** It was announced that Megalyn was supposed to reprise her role as Mari in Season 3 and meet Amaya, but for some reason that never happened.
** The show originally planned on tackling Ra's Al-Ghul and Damien Darhk's [[WeUSedToBeFriends friendship and fallout]] but was scrapped for unknown reasons.
** [[https://twitter.com/james_eagan/status/1072358719839748096 Other names]] for [[Recap/LegendsOfTomorrowS4E8LegendsOfToMeowMewow Legends Of To-Meow-Mewow]]