->"''If it isn't my old friends from Springfield, the Simpsons! What brings you folks to UsefulNotes/NewOrleans?''"
-->-- '''Chief Wiggum''', ''WesternAnimation/TheSimpsons'', "The Simpsons Spin-Off Showcase"

So, the SpinOff has launched. All the requisite cast members have jumped ship, and you've got enough stylistic elements to draw at least a loose connection between the new series and its parent. But why stop there? Why not have recurring visits from members of the old series, who are just stopping in to say hi? Hell, why not have {{crossover}} events?

A Required Spinoff Crossover is what happens when a spun-off series decides to showcase its connection to the original series in its first season, often and with great vigor at times. Sometimes it will happen when a character from the first series stops by to follow up on a plot in the second series. Other times, there will be a full-on crossover, where both series get together to follow one plot. Either way, the show is going to remind you of its pedigree as loudly as it can. Note that this is ''not'' [[{{Transplant}} a character from the first series moving to the second series]], but rather a periodic reminder, usually through guest appearance and crossover, of the connection between the two shows.
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!!Examples

* As the page quote indicates, ''TheSimpsons'' mocks this idea in the ''Chief Wiggum, P.I.'' segment of "The Simpsons Spin-Off Showcase."
** There's also ''The Lovematic Grampa'' from the same episode, where Homer stops by Moe's Tavern, and Abe calls his son out on the manner in which he buried his corporeal body ("You buried me naked and sold my suit to buy a ping-pong table!"). Homer responds by unplugging the love tester in which his father's soul resides and telling Moe, "Call me when you get a karaoke machine."
* ''Series/LawAndOrderSpecialVictimsUnit'' had Briscoe and Green from ''Series/LawAndOrder'' investigating a case that tied into Benson and Stabler's in "...Or Just Look Like One," and Abbie Carmichael served as the ADA in charge of SVU cases until they got their own ADA (first a minor character played by Reiko Aylesworth, then Alex Cabot). Furthermore, there was a crossover episode with the mothership, "Entitled," where SVU investigated the case in one episode and the DA's office prosecuted it in the next.
** ''LawAndOrderCriminalIntent'' followed the same pattern, with Briscoe and Green called upon to leak info of a serial poisoner by Goren and Eames in one episode, Van Buren asked about a suspect that formerly served under her in another episode, and Skoda called in for a psychiatric opinion in yet another episode. And before ''L&O: CI'' launched, there were plans for a "mega crossover" between the three series centered around a terrorist attack...[[TooSoon but then 9/11 happened]].
** The short lived ''Law and Order: Trial by Jury'' also did this, once with a follow-up on a case that had been closed on ''SVU'', and once with the prosecution of the guy who shot Det. Green on the original series. It's also noteworthy that Fred Thompson appeared on both ''Trial by Jury'' and the original ''Law & Order'' as a series regular on both shows simultaneously, a remarkably unusual occurrence in television history.
* ''Series/{{Angel}}'' had Oz and Spike showing up in one episode to follow up on plot from ''Series/{{Buffy|the Vampire Slayer}}'', Buffy showing up in "I Will Remember You," and Faith fleeing to LA after the events of "This Year's Girl"/"Who Are You?" with Buffy pursuing.
** Willow also showed up once to deliver news about Buffy, and again later when the AI team needed her to perform a spell.
*** Willow was the crossover once again in the season 9 comic series, appearing on the last page of Angel&Faith #10.
*** Before the license went back to DarkHorseComics Willow even managed to cross over ''between publishing companies'' to appear in IDW's ''Series/{{Angel}}'' spinoff, ''Spike''.
** There was also a special crossover "event" between the ''Buffy'' episode "Fool For Love" and the ''Angel'' episode "Darla", in which several flashback scenes are seen from Spike's perspective in the ''Buffy'' episode and then again from Darla's perspective in the ''Angel'' episode which originally aired immediately afterward.
** Season 6 and season 3 were the exceptions. Buffy changed networks in its sixth season and Angel's third and crossovers were banned. The reunion of Buffy and Angel after Buffy's resurrection was only visualized in comic book form. Fortunately, the networks changed the rules the next season.
* Consciously averted with ''Joey'', the spin-off of ''{{Friends}}'', if only because it didn't last long enough for them to try. The character moved from New York to L.A. so that the writers wouldn't have to explain why his best friends never visited him -- not that that worked for ''Frasier''...
* ''Series/DoctorWho'' occasionally does this in reverse, with Capt. Jack returning and revealing his connection to Series/{{Torchwood}} in the last three episodes of Series 3, and Torchwood and [[Series/TheSarahJaneAdventures Sarah Jane]] getting caught up in the Series 4 finale. The producers have gone on record that the Doctor will ''never'' appear in ''Torchwood'', as that would encourage Who's younger fans to watch a show which...isn't exactly aimed at them.
* TheBrigadier appears in the second season finale of the ''Series/DoctorWho'' spinoff ''Series/TheSarahJaneAdventures''.
** The Tenth Doctor appears in series three ("The Wedding of Sarah Jane Smith"). The Eleventh shows up in series four (''Death of the Doctor''), alongside another Classic Who companion, Jo Grant.
** It also features a Sontaran, the Slitheen and a Graske as recurring enemies, with the Sontaran's story being a direct continuation of what the Doctor did on his show.
* In ''Series/{{Torchwood}}'', ''Series/DoctorWho'' companion and Jack Harkness' ally Martha Jones appears in a few series 2 episodes.
** The episode "Cyberwoman" features a partially converted Cyberman from the aftermath of the ''Doctor Who'' series 2 finale.
* The pilot of ''MorkAndMindy'' had a "flashback" (filmed for the show) where Mork pays a visit to [[HappyDays the Fonz]] in the 1950s again. They even bring in Laverne from ''LaverneAndShirley''.
** Lampshaded by Mork himself as he reports to Orson after appearing as the new material holding together a "Happy Days" clip show later on in the season.
-->'''Mork''': Mork calling Orson....come in Orson....
-->'''Orson''': Mork! This is not your usual day for reporting back to me!
-->'''Mork''': Ah, quite true your Immenseness! But see, I did a spin-on to pay back for my spin-off.
** Of course, ''Happy Days'' and ''Laverne and Shirley'' had several crossovers themselves when both shows were set in Milwaukee.
* The second season premiere of ''Series/TheRopers'' featured a visit by Jack, Janet and Crissy. A later episode would have Larry Dallas dropping by.
-->'''Stanley Roper''': Larry! I'm glad to see you!\\
'''Larry''': You never were this glad to see me when I was your tenant.\\
'''Stanley Roper''': I was when you paid your rent on time!
* The first season of ''Anime/YuGiOhGX'' easily bears the closest resemblance to the original ''Anime/YuGiOh'' and even contains {{Shout Out}}s like Sho fantasizing that he and Judai are {{reincarnation}}s of an Egyptian pharoah and high priest. Pegasus and Kaiba appear with a fair amount of frequency as well, Sugoroku (Grandpa Muto) is featured briefly when the gang visit Domino City, and an early episode focuses on Judai dueling against someone who stole Yugi's old deck and is pretending to be him. [[spoiler:Yugi himself also appears, albeit shadowed, in the first and the penultimate episode, sending Judai back in time to duel the past Yugi when he still had Atem with him, to establish a fairly ridiculous time loop.]]
* The first episode of each new ''Franchise/StarTrek'' series featured a cameo appearance by one or more stars of a previous series.
** DeForestKelley (Dr. [=McCoy=] from ''Series/StarTrekTheOriginalSeries'') showed up in the series premiere of ''[[Series/StarTrekTheNextGeneration The Next Generation]]'' as an extremely aged Admiral [=McCoy=].
*** The Next Generation also got an epsiode focused on Sarek, Spock's father, a later two parter with Spock himself and single episode visit with Scotty.
** ''Series/StarTrekTheNextGeneration'' and ''[[Series/StarTrekDeepSpaceNine Deep Space Nine]]'' crossed-over for the "Birthright" two-parter.
** Picard appeared in the first episode of ''[[Series/StarTrekDeepSpaceNine Deep Space 9]]'' for a tense meeting with Sisko (whose wife had been killed at Wolf 359, when Picard was Locutus of Borg).
** ''[[Series/StarTrekDeepSpaceNine Deep Space Nine]]'' also brought Chief O'Brien over as a regular cast member from the beginning, in addition to having Lwaxanna Troi in a number of guest appearances. Even Kor, Kang, and Koloth from the [[Series/StarTrekTheOriginalSeries original series]] showed up as guest stars.
*** ''Voyager'' character Tuvok appeared in one of Deep Space Nine's AlternateUniverse episodes since the differences in timelines means that there was no reason for that version of the character to be trapped in the Delta Quadrant like the main universe version.
** ''[[Series/StarTrekVoyager Voyager]]'''s mission in the pilot episode started from ''[[Series/StarTrekDeepSpaceNine Deep Space Nine]]'', and an early scene had Tom Paris rescue Harry Kim from one of Quark's scams.
*** In fact, both ''[[Series/StarTrekDeepSpaceNine Deep Space Nine]]'' and ''Series/StarTrekTheNextGeneration'' featured season arcs revolving around the Maquis, which was created intentionally to serve as a plot device for ''[[Series/StarTrekVoyager Voyager]]'''s mission that resulted in it being stranded in the Delta Quadrant as well as its unusual crew dynamics.
** Deanna Troi and Reg Barclay from ''[[Series/StarTrekTheNextGeneration The Next Generation]]'' both had recurring roles on ''Series/StarTrekVoyager''.
** Jonathan Frakes appeared in all three spin-off series (as William Riker in ''[[Series/StarTrekVoyager Voyager]]'' and ''[[Series/StarTrekEnterprise Enterprise]]'' and as Thomas Riker in ''[[Series/StarTrekDeepSpaceNine Deep Space Nine]]'').
** ''Voyager'''s Captain Janeway got to make an appearance in ''Film/StarTrekNemesis'', which was a ''Next Generation'' movie. A torch passed back.
** Spock Prime (Creator/LeonardNimoy) appears in ''Film/StarTrek''.
* ''{{Frasier}}'' eventually had all his old friends (except Rebecca Howe) from ''{{Cheers}}'' visit him at least once. Also, his ex-wife Lilith became a RecurringCharacter.
** The creators have said that they chose Seattle specifically because it was on the other end of the country from Boston. A few thousand miles was enough to stop the higher-ups from pestering them all the time about when the Cheers gang was going to show up. It's not like Cafe Nervosa is on Cliff's mail route or anything...
** The earlier (and much more obscure) ''Cheers'' spinoff ''The Tortellis'' had an episode where Cliff and Norm just happen to show up...in Las Vegas, where the show was set.
* ''WesternAnimation/TheZetaProject'' had an episode featuring the second Batman; likewise, near the end of ''WesternAnimation/BatmanBeyond'', Zeta crossed back over.
* Inverted with ''[[OsuTatakaeOuendan Osu! Tatakae! Ouendan 2!]]''. For a limited time in 2007, Japanese gamers could go to download stations and download the ''EliteBeatAgents'' as playable characters.
* ''Series/TheManFromUNCLE'' and ''Series/TheGirlFromUNCLE'' featured Leo G. Carroll playing U.N.C.L.E. chief Alexander Waverly in both series. In addition, Robert Vaughn appeared as Napoleon Solo in the ''Series/TheGirlFromUNCLE'' episode "The Mother Muffin Affair", while Noel Harrison appeared as Mark Slate in the third season ''Series/TheManFromUNCLE'' episode "The Galatea Affair". The episodes were broadcast on the same week on NBC.
* The shows in Susan Harris' Miami sitcom universe (''TheGoldenGirls'', ''Empty Nest'', ''Nurses'') all featured these. There were two specific ones, specifically where events that began in ''TheGoldenGirls'' were brought to a close in the other two. A hurricane and a full moon began some chaos that would be fixed in the hospital where Harry Westen of ''Empty Nest'' and the ''Nurses'' worked. Might make it a CrisisCrossover.
* ''DiffrentStrokes'' and ''Series/TheFactsOfLife'' had a number of these early in the latter show's run.
** Meanwhile, a "connection" between ''Diff'rent Strokes'' and ''Hello Larry'' was contrived after the fact (having Mr. Drummond buy Larry's radio station) for the express purpose of setting up crossovers to try and help the latter show's popularity. It didn't work.
* ''Manga/ACertainScientificRailgun'''s spin-off protagonist Mikoto Misaka will (most of the time) run into the series protagonist [[{{ToAruMajutsunoIndex}} Touma Kamijou]]. And most of the time, Mikoto WILL challenge Touma because of his [[{{AntiMagic}} Right hand]] cancelling her Railgun. And they'll tie.
** The anime also threw in cameos of other Index characters, such as [[EmotionlessGirl Aisa]] or [[SenseiChan Komoe]].
* Just about the entire ''MaryTylerMooreShow'' cast turns up in ''Rhoda'' for the title character's wedding, eight episodes or so into the first season. This is sweet, but a bit awkward...maybe WJM's ratings were so low, no one would notice if the news took a day off.
** Hard to believe, but those who work in the news are allowed to have a day off. There is indeed a "weekend" crew at almost every local news outlet.
* Similar to the ''Law and Order'' examples above, ''{{CSI}}'' occasionally does crossovers with its spinoffs. Aside from the pilot of one spinoff being an episode of a previous series, ''CSIMiami'' and ''CSINewYork'' crossed over once, and all three crossed over recently for a story involving human trafficking.
* [[WesternAnimation/HeManAndTheMastersOfTheUniverse1983 He-Man]] would often show up on ''WesternAnimation/SheRaPrincessOfPower''.
* ''Series/StargateAtlantis'' has featured each member of the original cast of parent series ''Series/StargateSG1'' in at least one episode each, often to contrast their spinoff counterpart. The producers made a deliberate effort to tie ''Atlantis'' back into ''SG-1'', too - the original series got an episode set in the spinoff's location.
** ''Series/StargateUniverse'' has SG-1 characters turn up often (minus Teal'c who is DemotedToExtra, for some reason). O'Neill in particular is around more now than he was in the final seasons of his own series. The first season finale, involving SG-1 bad guys trying to reach the ''Destiny,'' is set to be as much an episode of SG-1 as SGU, if the episode that serves as prelude is any indication.
** O'Neill's case makes a lot of sense, as he is currently the head of Homeworld Security, and the situation involving Project Icarus and ''Destiny'' are likely to need his oversight. You know, since Icarus Base was destroyed and most of the people in charge were killed or stranded on ''Destiny.''
* ''Series/NCISLosAngeles'', which got its start on a PoorlyDisguisedPilot on the regular ''Series/{{NCIS}}'', featured the DC team's Abby coming out to L.A. to investigate a serial murder case. The episode pretty much revolved around her.
** Similarly, Bud Roberts from ''Series/{{JAG}}'' appears on an early episode of ''NCIS''.
** Lee Wuan Kai, a Korean assassin, had a history with Leon Vance, director of NCIS. So, naturally, her first stop was Los Angeles not long after they get established, causing Leon to fly out to deal with things [[ItsPersonal personally.]] Then she followed him back home.
* In the very first ''VideoGame/WarioLand'', a statue of [[SuperMarioBros Princess Peach]] is the game's MacGuffin. Mario himself appears at the end of the game to take the statue away from Wario.
* In ''TheClevelandShow'', one one-off gag features Chris appearing in Cleveland's house for no reason. ("Go back to Quahog!") Another episode features the death of Cleveland's ex-wife as an important plot point, giving an excuse for Quagmire and Peter to show up. Cleveland and his family also reappeared in a ''FamilyGuy'' episode.
* {{Subverted}} with ''{{Daria}}'' and ''BeavisAndButthead.'' Initially there were plans to do a crossover, but it quickly became apparent that the two shows had a very different tone and were likely to attract different audiences. As a result the only mentions of B&B in ''Daria'' canon are a few sparse mentions of the family moving from Highland.
* [[AllInTheFamily Edith Bunker]] dropped by to visit [[TheJeffersons Louise Jefferson's]] deee-luxe apartment in the sky.
** Although {{Maude}} appeared in a ''BackdoorPilot'' which featured Edith and Archie also dropped in on her cousin {{Maude}}, they never showed up on the actual spin-off.
* [[HerculesTheLegendaryJourneys Hercules]] and {{Xena}} frequently crossed over into each other's shows.
** As did several characters of varying importance (from gods to comic relief)
* The Laird of the Glen's single appearance in ''Radio/ImSorryIHaventAClue'' might qualify. The Laird was created for the sitcom version of Graeme and Barry's "Hamish and Dougal" skits and played by Jeremy Hardy. So when Jeremy stood in for Graeme as Barry's teammate, it only made sense to do a "Dougal and the Laird" skit.
** The ''HamishAndDougal'' Hogmanay Special was a straighter example. ''Hamish And Dougal'' was spun off from ''Radio/ImSorryIHaventAClue'', and the Hogmanay Special brings in all of Clue's regulars.
* Done frequently with ''WesternAnimation/DoraTheExplorer'' and its spin off ''WesternAnimation/GoDiegoGo''.
* ''Series/BarneyMiller'''s Dietrich stopped by to visit Fish in the latter's spinoff show.
* ''AoiShiro'' has the appearance of Asama Sakuya from ''AkaiIto'', who turns out to be Aoi-sensei's drinking buddy. The manga turn it UpToEleven by [[spoiler:making Wakasugi Tsudura and her group TheCavalry, with Hatou Kei's blood required to thwart Ba Rouryuu's plan]].
* This used to happen all the time in the ''Franchise/KamenRider'' series starting with ''Series/KamenRiderV3''. With ''V3'', Ichigo and Nigo helped turned Shiro into the titular Rider before they were supposedly killed. Then they came back to help him and Riderman. Then, every series through the Showa era would have every previous Rider return to help the current Rider save the day.
** ''Kamen Rider'''s Heisei era developed a tradition of these starting with ''[[Series/KamenRiderDecade Decade]]''. Rider A's standalone movie (which occurs late in its run), will have Rider B (star of the upcoming series) make an EarlyBirdCameo, usually appearing from nowhere to help Rider A battle some powerful enemy. Then shortly into Rider B's run, there will be a crossover film (dubbed "Movie Wars") where A and B each get their own mini-movie segment, and it all ends with the two heroes joining forces to fight the film's BigBad. These crossovers are apparently {{Canon}}, at least to each other, since when the characters meet up for the second time they'll reference the events of their first encounter.
*** ''SuperSentai'' has also adopted this format, though due to the difference in the timing of new season launches between them and ''Kamen Rider'', the EarlyBirdCameo Rangers usually show up in the crossover feature, not the standalone one.
* Several major characters from ''TheWotch'' make significant or cameo appearances in ''{{Cheer}}''. For example, the arc where Alex tries to find new cheerleaders has Wolfie and Ming try out and make the cut, while Jason is bribed into helping with the tryouts.
* ''{{CSI}}'' has had several, aside from the pseudo-crossover PoorlyDisguisedPilots.
** Ray Langston visited both other series during CSI's 9th season.
** In CSI NY's second season,[[{{CSI NY}} Mac Taylor]] went down to Miami and then returned to New York with [[CSIMiami Horatio Caine]] as they tried to catch a suspect together.
** The original and CSI NY crossed over when Mac went to Las Vegas to surprise his girlfriend/future fiance and discovered she'd been kidnapped. When he and DB Russell realized she'd never left New York and was being held there, Mac returned to NY with DB in tow to find her before it was too late.
*** Incidentally, the original never crossed with the spinoffs until after William Petersen's departure, because he was against the spinoffs from the start, believing it watered down the writer pool on the original.
* Just after the premiere of the ''{{Bones}}'' spinoff ''Series/TheFinder'', Lance Sweets appeared on a an episode. Jack Hodgins also subsequently appeared in another ''Series/TheFinder'' episode.
* ''Series/PowerRangersLostGalaxy'', the first ''Franchise/PowerRangers'' season to be a spin-off rather than a direct continuation, had the main cast and characters from previous series, ''Series/PowerRangersInSpace'' teaming up to fight revived PsychoRangers. Not only that but [[spoiler:Kendrix died and Karone, better known as former ''In Space'' villain Astronema, replaced her as the Pink Galaxy Ranger]]. Since then it became tradition (though one not always held to) for new ''Power Rangers'' series to have a crossover with previous one.
** [[MilestoneCelebration Anniversary seasons]] (''Wild Force'', ''Operation Overdrive'', ''Megaforce'') often celebrate by bringing back Rangers from previous series for a special episode.
** Besides the ''in Space'' teamup described above, ''Lost Galaxy'' also had established connections to ''in Space'' by having Bulk, Skull and Professor Phenomenous appear in the first episode and Alpha 6 and the Astro Megaship in the second one.
** ''Series/PowerRangersDinoThunder'': During Mesogog's first attack, he expected people to believe that last season's villain, [[Series/PowerRangersNinjaStorm Lothor]], was responsible despite it not being the same town Lothor used to attack. Later on, a two-part episode featured Lothor and the Ninja Storm rangers.
*** Also, [[Series/MightyMorphinPowerRangers Tommy]] was the Dino Thunder Rangers' mentor.
** ''Series/PowerRangersSPD'' had ''two'' crossovers with ''Series/PowerRangersDinoThunder'', with each team getting to visit the setting of the other's show.
** ''Series/PowerRangersMysticForce'' had [[Series/PowerRangersSPD Piggy]] making an appearance and making a CallForward to [[TwentyMinutesInTheFuture events from the SPD series]]. It also stated that one minor character, Mystic Mother, was [[spoiler:a redeemed [[Series/MightyMorphinPowerRangers Rita Repulsa]]]].
** ''Series/PowerRangersSamurai'''s crossover with ''Series/PowerRangersRPM'' only barely qualifies, though - only one RPM Ranger shows up, and he was a FakeShemp to boot.
*** [[Series/MightyMorphinPowerRangers Bulk]] was a regular along with [[SpinOffspring Skull's son]]. Skull appears in the finale.
* Notably averted in ''BostonLegal'', where none of the regulars on ''ThePractice'' stopped by for guest spots (likely attributed to the spinoff characters having been introduced [[PoorlyDisguisedPilot as stars of the latter's final season]]). This can alarm some viewers who notice that guest stars on ''The Practice'' like John Larroquette and Rene Auberjonois ended up starring on ''Boston Legal'' [[YouLookFamiliar as completely different characters]].
** Bill Smitrovich, who portrayed Assistant District Attorney Kenneth Walsh in ThePractice, portrayed another prosecutor in ''BostonLegal''. Smitrovich's character in the spinoff worked in a state where death penalty was an option.
** The law firm of Young, Frutt and Berlutti was once mentioned in BostonLegal.
* In ''ThePerilsOfPenelopePitstop'', there was a scene where the Hooded Claw asked Penelope if she was expecting [[WackyRaces Dick Dastardly]].
* The main field cops of ''Series/TokkeiWinspector'' returned for a three-part episode of ''Series/TokkyuuShireiSolbrain''. It was only some episodes later one of them became a regular in ''Solbrain''.
* While they never acted like it was just a SpinOff, WebVideo/TheNostalgiaCritic popped up a lot more in WebVideo/TheNostalgiaChick's show than anyone else's. [[spoiler: Not even his death could stop it.]]
* ''VideoGame/AngryBirds'' has it both ways. The spinoff ''VideoGame/BadPiggies'' features a cameo from the Blue Birds in the episode "When Pigs Fly", and the birds themselves can be found sleeping in "Flight in the Night". Meanwhile, ''Angry Birds'' itself debuted a new episode entitled "Bad Piggies", which features the same setting and characters as the game it is named after.
* ''SamAndCat'' has the Robbie character from ''{{Victorious}}'' show up in Episode 4.
* Is there a song that's popular on just one Franchise/{{Bemani}} game (i.e. ''VideoGame/{{Beatmania}}'', ''VideoGame/{{Jubeat}}''. ''VideoGame/DanceDanceRevolution'')? Expect to see it on ''every other sister game'' during the next cycle of releases. The most infamously wide-spread examples of this have included "Rin to shite saku hana no gotoku" (a.k.a. "Nadeshiko Rock") and "FLOWER"; the latter even made it onto ''VideoGame/{{Gitadora}}'' too, in the form of a one-to-one rock remix, and also ''VideoGame/SoundVoltex'' in the form of a [=REDALiCE=] remix (until the advent of ''SOUND VOLTEX II''[='=]s POLICY BREAK event, Konami orignials were not allowed in the game).
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