Series that began life as prime-time specials, sometimes related to holidays. This seems to particularly be the case with adaptations. Seemed to be very popular in TheEighties.

Compare PoorlyDisguisedPilot, FiveEpisodePilot. Sometimes overlaps with PilotMovie.
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!!Examples:
* ''TvsBloopersAndPracticalJokes'' was a merging of three previous NBC specials...''Johnny Carson's Funniest Practical Jokes'', ''TV's Censored Bloopers'', and ''TV's Greatest Commercials''. Reversed after the show was cancelled and ''TV's Censored Bloopers'' was presented again as an occational series of specials.
* TLC likes to test show concepts this way. That's how we got ''JonAndKatePlusEight'', ''Series/NineteenKidsAndCounting'', and ''TableForTwelve'', among others.
* ''ACharlieBrownChristmas'', ''[[ItsTheGreatPumpkinCharlieBrown It's the Great Pumpkin, Charlie Brown]]'' and the other ''{{Peanuts}}'' specials in that sequence eventually led to ''The Charlie Brown and Snoopy Show''. This one is a case where the specials are currently more famous than the show they launched.
* {{Garfield}} had several specials under his belt before ''GarfieldAndFriends''.
* ''GIJoe'' had two mini-series before the actual series began.
* ''Franchise/MyLittlePony''
* ''WesternAnimation/TheSimpsons'': "Simpsons Roasting on an Open Fire" aka "The Simpsons Christmas Special" was always intended to be just one more episode of the show, but the fact that Fox chose[[note]](or, since the original animation for the first few episodes was coming back so poorly the entire series had to be slipped, but the Christmas episode, #8, had to air around Christmas)[[/note]] to air it as the first episode is probably due to the influence of this trope.
* Similar to the Simpsons example, the 2008 ''GeorgeOfTheJungle'' series started with a Christmas special.
* ''WesternAnimation/AllGrownUp'' was originally a special, but was popular enough that they made it a successor series to ''{{Rugrats}}''.
* ''Series/TheAdventuresOfPeteAndPete'' started out as a series of shorts during commercial periods, followed by full-length specials, then the regular series.
* ''StrawberryShortcake'' was originally just a series of specials. When she was revived in the 21st century, she got a proper TV series.
* ''Series/TheSarahJaneAdventures'' began with a New Year's special, but had been commissioned for a full series prior to the filming of the special.
* ''TheRaccoons'' originally had four specials. The first one being about Christmas.
* ''Series/BoSelecta'', or at least lead character Avid Merrion, started as filler shorts during adbreaks for one season of ''BigBrother Live''.
* This is very much the purpose behind ''ComedyLab''.
* The ''OnePiece'' Christmas special was originally supposed to be a two-episode filler where the cast is in feudal Japan and Luffy is a detective, but later evolved into reoccurring filler episodes. They were easy to plot, genuinely funny, could be fit in at any time, and brought back a lot of old characters in as cameos.
** Chopperman was given his own series. It began as a tiny short, then turned into some successful merchandise, and now it stands on its own two feet.
* The Australian show ''GoodNewsWeek'' was canceled back in 2000. In 2008, a reunion special was planned, but the Writer's Guild strike in America caused Channel Ten to revive it fully.
* Another Aussie example, ''[[HeyHeyItsSaturday Hey, Hey, It's Saturday]]'', was a variety show that was on air for nearly 30 years, starting as a childrens program and eventually becoming a prime time variety show, in 1999 the show was wrapped up, but in 2009, 2 one off reunion specials were aired on consecutive Wednesdays. These specials were a runaway hit and this resulted in the show now being back on air every Wednesday.
* ''{{Madeline}}'' (the animated series) started as a series of TV specials in the late 1980s-early 1990s. She had her own TV series from 1993 to 2001.
* ''TransformersGeneration1'': The [[WesternAnimation/TheTransformers original cartoon]] started out as a three-part serial.
* ''Series/AmericasFunniestHomeVideos'' began as an hour-long special hosted by Creator/BobSaget and Kellie Martin in November 1989; it was brought back as a weekly series two months later with Saget in tow, and has aired ever since with two host changes since then (with the minor exception of a period from the fall of 1998 to the summer of 2001, when in an inversion of this trope, it was reduced to a series of specials).
* ''Series/TenOClockLive'' started out originally as ''Channel 4's Alternative Election Night''.
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