So, you're shooting a weekly TV series, but one of your actors can't make it that week because of [[RealLifeWritesThePlot illness/rehab/a lengthy film shoot]] and the scripts are already written with a big role for their character? What do you do? Call in a Temporary Substitute, of course!

Similar, but not identical, to a SuspiciouslySimilarSubstitute. This is where a script has clearly been hastily rewritten to give one character the plot that would have been given to the character who can't make it that week. That it may involve someone being NotHimself for the week is often unavoidable. A SuspiciouslySimilarSubstitute is permanent, a Temporary Substitute is (hopefully) temporary; the lines blur, of course, when you're not sure if the original character is going to come back.
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!!Examples:

[[folder:Live-Action TV]]
* ''Series/{{Frasier}}'' has done this once, in the episode "Head Game." Originally written for Frasier, it was rewritten for Niles due to Kelsey Grammer being in rehab. The opening scene featuring Frasier that explained his absence was filmed many weeks later.
* The first five episodes of ''Series/StargateSG1'''s ninth season lacked Samantha Carter because Creator/AmandaTapping was nine months pregnant at the time of filming. As a result, all of the "sciency" dialogue was given to a recurring, relatively unimportant, base scientist.
** In the pilot episode of ''Series/StargateAtlantis'', there was going to be a scientist by the name of Dr. Ingram, whose actor backed out late in the game. Reaching back into [=SG1=] Recurring Character Land, they found Rodney [=McKay=], called up David Hewlett, and gave him all of Ingram's lines.
* During filming of the ''Series/StarTrekTheOriginalSeries'' episode "The Gamesters of Triskelion", George Takei was busy filming the movie ''The Green Berets''. Chekov took his place in the script, with a barroom brawling style in the episode's fight scenes taking the place of the martial arts scenes planned for Sulu.
** Ditto "The Trouble With Tribbles"; Chekov's instant recognition of quadro-triticale made more sense when the script was written for Sulu, as Sulu had an established background in botany.
** There are a handful of episodes in which Uhura fails to appear at the communications station and a temporary character takes her place.
* The ''{{CSI}}'' episode "Gum Drops" was originally going to have Gil Grissom thinking a missing child was still alive. When a death in the family took William Petersen out of town, Nick Stokes became the lead investigator on the case.
** Much like "Gum Drops," the episode "Genetic Disorder" originally had Nick as the lead, but had to be hastily rewritten with Greg Sanders as the lead as George Eads was attending the funeral of his father.
* When Lucy Lawless was injured doing a stunt for ''The Tonight Show,'' a single episode of ''XenaWarriorPrincess'' where Xena and Callisto changed bodies became a two-episode-arc with Hudson Leick playing Xena (trapped in Callisto's body).
* Samaire Armstrong entered rehab in the fall of 2007 for undisclosed reasons and had to be written out of an episode of ''Series/DirtySexyMoney.''

* On ''Series/{{Angel}}'', Wesley was absent for one Season Five episode, because Alexis Denisof was on his honeymoon with Alyson Hannigan. He was replaced for the episode by another expert on occult lore, with the explanation that Wesley was taking some well-deserved time off after [[spoiler: killing a robot that he believed to be his father]].
** This one is unusual in that Joss probably knew about this months in advance, enough time to not only set up the reason for Wesley's absence, but write an episode that would not have worked if Wesley had been present - a major plot point was that the Substitute Expert was evil, and deliberately mistranslated a text, where Wesley would have given a faithful translation.
* During its early years, the Mexican sitcom ''Series/ElChavoDelOcho'' was incredibly nonchalant about using act-alike, dress-alike characters with different names whenever one of the regulars was unavailable. Don Ramón, for example, was replaced for a single episode by his "cousin, Don Román" who did everything Don Ramón would ordinarily do, including freely enter and exit Don Ramón's apartment. Another time, Doña Clotilde was replaced for a couple of episodes by a new neighbor named Doña Eduviges, who apparently moved away again as soon as Doña Clotilda came back.
* When Jason David Frank took time off to visit his family in Texas, the producers of the New Zealand-filmed ''Series/PowerRangersDinoThunder'' were forced to first trap his character, Tommy Oliver, in Ranger form, and later, render him invisible for two episodes. Since Tommy is a high school science teacher by this point in the franchise, they also had to grab several Substitute Teachers. To make things significantly more interesting, one of the substitutes was the [[JekyllAndHyde human form]] of the BigBad.
* A rather unique example, also from ''LawAndOrder'': When Jill Hennessey’s character Claire Kincaid made a crossover appearance on ''HomicideLifeOnTheStreet'', conflicting and overlapping production schedules forced producers to [[MakingUseOfTheTwin recruit her identical twin sister Jacqueline]] (a host and occasional actress on Canadian TV) to double for her sister in a few courtroom scenes. This unusual substitution, in the episode "Corpus Delicti," was not credited on-screen.
* ''Series/DoctorWho'':
** ''[[Recap/DoctorWhoS2E2TheDalekInvasionOfEarth The Dalek Invasion of Earth]]'': Star William Hartnell was injured in an action scene in this story. So in the next episode, the Doctor is knocked out in an injury (played by a double), and his lines (and technical skills) are given to a freedom-fighter character from the story. (Hartnell was back in the next episode).
** ''[[Recap/DoctorWhoS10E5TheGreenDeath The Green Death]]'' has a case with the guest cast, Tony Adams, the actor playing Elgin fell ill between recording sessions, so in episode 5 a Mr James appears instead. Which leads to a bizarre situation of a character being set up to betray the bad guys - then someone else turns up out of nowhere to do it instead.
*** Even weirder because they could have easily explained his replacement, but didn't. Elgin was subjected to a mind control technique, which had caused another character it was used on to commit suicide earlier in the story. So they could have justified Elgin's replacement by having it explained that he took his life, or by shooting a suicide scene with a stunt man.
** ''[[Recap/DoctorWhoS6E2TheMindRobber The Mind Robber]]'': Frazier Hines got chicken pox during filming. A scene was quickly inserted where the Doctor has to reassemble Jamie (it really does [[ItMakesSenseInContext make sense in context]]) and accidentally used Hamish Wilson's face. Later in the episode, a second put-Jamie-back-together brought Hines back once he got better.
* ''Series/GetSmart'' has "Ice Station Siegfried," where Don Adams' Maxwell Smart is replaced by Bill Dana's CIA Agent Quigley for an episode.
* With Mary Jo Pehl busy in Los Angeles filming scenes with Leonard Maltin for the ''Film/{{Gorgo}}'' [[Recap/MysteryScienceTheater3000S09E09Gorgo episode]] of ''Series/MysteryScienceTheater3000'', she was unable to play the role of Pearl in the ''Film/TouchOfSatan'' [[Recap/MysteryScienceTheater3000S09E08TouchOfSatan episode]]. Hence, it was explained that Pearl went on vacation and hired a babysitter to watch over Prof. Bobo and the Observer while also informing Mike and the 'Bots about the film they were going to watch.
* When Kathryn Erbe got pregnant during Season 3 of ''LawAndOrderCriminalIntent'', the character of G. Lynn Bishop was brought in as a replacement. Erbe was still seen in those episodes, but she stayed behind a desk.
* When Lynda Day George became pregnant at the end of season six of ''Series/MissionImpossible'', ex-con Mimi Davis was written in for a handful of episodes the following season.
* In the older ''Series/RandallAndHopkirkDeceased'' series, there's one episode, "The House on Haunted Hill" in which Jeannie does not appear. Her sister Jenny had appeared in an earlier episode, so the characters mention right at the beginning that Jenny is filling in for Jeannie at the office, and then act exactly as usual for the rest of the episode.
* One episode of ''Series/{{Battlestar Galactica|Reimagined}}'' involved a debate over whether it was justifiable to infect the Cylons with a deadly disease. The script called for someone to [[StrawmanBall push very strongly in favor of it]]. Normally this would be established Cylon-hater Colonel Tigh, but due to another storyline Tigh was currently AchillesInHisTent. So the writers pressed Lee Adama into service to clumsily understudy for him.
* In the first season of ''[[Series/ThirtyRock 30 Rock]]'', Jonathan disappeared for two episodes. A character called Matt filled in as Jack's assistant until Jonathan's return.
* On ''Series/{{Mythbusters}}'', Kari Byron went on maternity leave, and was replaced by Jessi Combs for a few months.
* One episode of ''{{Monk}}'' featured only Tony Shaloub and none of the other regular cast members, as due to some trouble behind the scenes it was essentially written that way by the crew as a warning that they could still do the show without them. Since this meant Monk's regular assistant Sharona was absent, recurring character Kevin Dorfman served her usual role instead.
* ''Series/KamenRider'' is a rather famous example; star HiroshiFujioka was injured in a stunt gone wrong, which forced the writers to create a second Kamen Rider (Hayato Ichimonji) while the original (Takeshi Hongo) was fighting off-screen enemies. Fujioka eventually returned and took the reins back, but some episodes featured both Riders joining forces, and both heroes are viewed as equally iconic and popular by the franchise's fanbase.
* ''Series/TheDukesOfHazzard'' had almost an entire season of Temporary Substitutes when Bo and Luke went off to race in NASCAR (or, in reality, contract disputes) and their strangely identical cousins turned up instead, hanging around until the other two returned. Toes the line between SuspiciouslySimilarSubstitute and Temporary Substitute.
** Sheriff Rosco Coltrane also got a couple of of these when actor James Best boycotted part of the second season, citing unsafe dressing-room conditions. One of the Temporary Substitutes was Dick Sargent, best known as the literal [[TheOtherDarrin Other Darrin]].
*** Cooter also got a couple of different substitutes that same season, when Ben Jones boycotted the show after the producers asked him to shave off his beard.
* ''The Memoirs Of Franchise/SherlockHolmes'' dealt with the illness of its leading man, Jeremy Brett, by invoking both Watson and Mycroft as Temporary Substitutes. This gave Watson back some of the competence his traditional portrayals had lacked, and made Mycroft a lot more active than he ever was in the canon.
** To be clear, that was really only invoked in "The Mazarin Stone", as Jeremy Brett was (to put it bluntly) dying. In other episodes, Watson does have more of a role, and even some of Holmes' lines (such as the solitary cyclist) - this was not done for Brett's health, but to even the relationship and make it clear he wasn't the bumbling idiot that popular opinion holds so dear.
* Connie Nielsen as Detective Dani Beck replaced Olivia Benson for eight episodes on ''Series/LawAndOrderSpecialVictimsUnit'' while her actress Mariska Hargitay was on maternity leave.
* With Jesse L. Martin committed to the filming of ''Theatre/{{Rent}}'' in 2005, his character Ed Green on ''Series/LawAndOrder'' was shot late in the season and spent the remaining four episodes recovering in the hospital. Michael Imperioli took over as Fontana's temporary partner Nick Falco for the duration. Unlike most other out-of-nowhere Temporary Substitute, Falco made an additional appearance the next season in a non-substitute capacity.
* In one episode of ''Series/ThePrisoner'', "Do Not Forget Me Oh My Darling," V had Number Six's mind swapped into another man (played by Nigel Stock), since Patrick [=McGoohan=] was off filming ''Ice Station Zebra'' at the time.
* ''Series/HogansHeroes'' had at various times temporary replacements for Carter and Newkirk. Kinchloe was replaced by a SuspiciouslySimilarSubstitute in the last season.
* When JJ Jareau (and her actress AJ Cook) took maternity leave on ''Series/CriminalMinds'', she picked Jordan Todd (played by actress Meta Golding) to fill in for her.
** An interesting case, this one. Since everyone had lots and lots of prior notice about AJ Cook's leave (her pregnancy storyline started the season before), Todd's role is not just a re-writing of scripts written for JJ: she has her own character, arc, and thematics, all of which are very different from JJ's. At the same time, she fills the same role in the team bureaucracy that JJ does.
* At the end of the fifth season of ''Series/StepByStep'', the actor who played Cody was unavailable to shoot the two-part Disney World episode--quite a loss, since the episode revolved largely around Cody's effort to go on every ride in the park in record time. Instead, a new character named Flash (apparently Uncle Frank's employee) shows up unannounced and proceeds to do everything Cody was intended to do, making him the effective star of the show for these two episodes. He made one last appearance in the season finale which actually had him moving into the Foster/Lambert household, setting him up as a full-fledged SuspiciouslySimilarSubstitute, before being scrapped in favor of Bronson Pinchot as zany Frenchman Jean-Luc and Jason Marsden as J.T.'s friend Rich as new regulars. Cody was explained as having [[PutOnABus boarded a bus for Russia]], but he would return for a final season episode.
* Variation on ''Series/ForeverKnight'': Some of the scripts originally written with Captain Stonetree in season 1 were stashed away and used with Captain Reese in season 3. The two captains even both have the first name "Joe".

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[[folder:Film]]
* In the third ''Film/HarryPotter'' film, Goyle is replaced in several scenes by a random Slytherin boy. Apparently, Josh Herdman had suffered an injury and was unavailable when they had to shoot those scenes. Goyle resumed his usual role in all subsequent films and his replacement was never seen again. Fans like to imagine that the unnamed replacement character was Theodore Nott, a Slytherin student in the books who otherwise has never appeared in the movies.
** The same character also got to be on the other end of this trope. After Jamie Waylett's RoleEndingMisdemeanor, Crabbe was written out of the last movie and his big scene [[spoiler:(a death scene, ironically)]] was given to Goyle instead.
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[[folder:Web Original]]
* Amandine Train, Saphir's actrice, was pregnant during the filming of Season 5 of ''Series/{{Noob}}''. However, Saphir also had the important task of [[spoiler:getting Omega Zell ready for high-level play]] during that portion of the story. One episode filmed during the last months of her pregnancy had her use and avatar looking just like Gaea, which made Gaea's actrice play in the in-game scenes while some of her dialog had the camera do SplitScreen between the avatar and her player in front of the computer with only her face visible. Later episodes outright had Saphir need to complete an urgent quest off-screen and call in her sister to take care of her everyday work, including the stuff happening onscreen.
[[/folder]]

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