->'''Announcer:''' The start of television's second most exciting season - midseason - is just two hundred exciting seconds away!
->'''Lisa:''' Isn't midseason just a dumping ground for second-rate shows that weren't good enough for the fall schedule?
->'''Homer:''' You're thinking of all the other years.
-->--''WesternAnimation/TheSimpsons'', "Homer to the Max"

If a show's really, really lucky, it'll last a number of seasons. Some shows are lucky to get one. Meanwhile, some of the new programming premiering at the beginning of a season flops so badly that it's canceled before even being allowed to complete a full run.

This leaves the [[{{Networks}} network]] with an uncomfortable situation - how to fill out the rest of the season. Often, networks will throw up reruns of popular shows in the failed show's timeslot, or fill the void with {{Made For TV Movie}}s or other special programming. The usual go-to guy for such a situation, however, is the Midseason Replacement.

The Midseason Replacement is typically a show network execs don't consider strong enough to premiere at the beginning of a season, but is held in reserve for a premiere later when time slots are needed to be filled after another show has gone belly-up. Since the midseason replacement is considered to be a weaker show than what the network was originally hoping for, expectations often aren't very high. Another reason a show might be a midseason replacement is because of production problems - ''TheSimpsons'' is one such notable example, as is ''Series/StarTrekVoyager'' which simply had to wait for the rest of the network to premiere. Also, due to the need to stretch out episodes if a show airs over the entire TV season (September through May), a show may premiere midseason simply so they can air all the episodes with few or any breaks (this is especially common for serialized programming or reality shows).

Midseason replacements premiere, as the trope name suggests, in mid-season, which is typically anywhere from late December to early May. Any date later than that, and it's considered a '''late season replacement''', which can premiere from late May into June. Late season replacements are usually considered by networks to be very weak shows, may have only a very limited number of episodes ordered, and are considered to have almost no chance of actually being picked up. Cancellations before the show even premieres are not rare. A late season replacement may result from a network wishing to fill gaps in its summer programming, to provide an alternative to summer rerun schedules, or may have been originally slated as a potential midseason replacement but in which feared gaps in midseason programming never materialized.

Note that this trope only specifically applies to broadcast network programming in the United States; different countries have different conventions, and the practices of cable networks in the United States may vary just as greatly. For example, USA Network's ''{{Monk}}'', generally considered to be one of the strongest shows on cable, premiers new episodes in the middle summer months ''and'' winter months, in a unique (though common practice on USANetwork) season split-up.
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!!Inversions

* ''WesternAnimation/TheSimpsons'': It was ''meant'' to be a fall premiere, but several early episodes had to be re-animated.
* ''[[Franchise/LawAndOrder Law & Order]]''
* ''{{Seinfeld}}''. It was threatened with cancellation at the conclusion of its initial season, a sparse 5 episodes, but was given a second chance, and the rest is history.
* ''AllInTheFamily''
* ''SanfordAndSon''
* ''Series/BuffyTheVampireSlayer''. Its first season was only twelve episodes. Sarah Michelle Gellar even commented that when she told people what she was working on, they said she would get something better next season.
* ''FamilyGuy'' - having been canceled and then UnCancelled is notable enough, but its "uncancellation premiere" almost qualifies as a late season replacement having originally premiered the first week of May 2005. In a rare case of tactful thinking, FOX executives were confident enough of the show's popularity to bring in huge ratings despite the late premiere date.
* ''WesternAnimation/AmericanDad'' likewise followed ''Family Guy' for its premiere on the first week of May 2005.
* [[RealityShow Reality Shows]] very frequently have midseason or late season premieres as emergency replacements for programming that has failed unexpectedly. Networks have pretty much refined the quick formulation, production and execution of reality shows (often in a matter of weeks from conception to premiere at most) to a fine art at this point.
* Most prime-time AnimatedSeries are intentionally midseason replacements, the reasoning being that they're more expensive and time-consuming to produce and the networks don't want to have it all go to waste if the show bombs. So the first season is intentionally made shorter as a sort of trial run.
* ''Series/StarTrekVoyager'' premiered in January, launching the UPN network. ''Series/StarTrekDeepSpaceNine'' also began its run in January. Both had shortened first seasons (albeit only marginally so for ''Deep Space Nine''), and both did well enough to last seven seasons.
* ''TowardTheTerra'' is an anime example. After ''AyakashiAyashi'' flopped so badly that was canned midways, ''Terra'' was allowed to fill the gap, occupying TBS's anime primetime slot that previously housed "A grade" shows like ''GundamSeed'', ''Anime/FullmetalAlchemist'' and ''BloodPlus''.
* ''TheOffice'' was not only a midseason premiere, it almost didn't last to a second season.
* ''QuantumLeap''.
* ''Series/TheATeam'' premiered in midseason in 1983 and ran successfully for five seasons before {{Cancellation}}, although it did have the advantage of going after the SuperBowl. It still has a {{Cult|Classic}} fanbase and spawned a [[TheMovie Movie]] in 2010 (some 27 years after its premiere).
* ''{{Airwolf}}'' ran for three seasons after a SuperBowl launch on CBS and for a fourth on USA.
* ''GreysAnatomy''
* ''Series/{{Castle}}'' aired only ten episodes in its first season in a replacement slot after ''DancingWithTheStars''... it's still there and has gotten a seventh season.
* Most seasons of Franchise/PowerRangers ran from February to November, despite originally premiering in the fall. The reason is that the continually shrinking source footage was wearing thin and the third season had a truncated number of episodes, so they created a mini-arc called "Mighty Morphin' Alien Rangers" (where the main team's morphing powers were destroyed and they called in to an alien Ranger team to protect the Earth) which served as a bridge between ''Series/MightyMorphinPowerRangers'' and ''Series/PowerRangersZeo'' (where new powers are forged for the main team and the alien Rangers return home).
* ''Series/TwentyFour'''s first three seasons all started in September and ran until May, but complaints about a show in real time being stretched out over the entire season caused them change to a "non-stop season" format beginning with season 4, in which every week had at least one new episode; for obvious reasons, for the finale to happen in May, the show had premiere midseason.
* ''Series/TheInvaders'', which premiered in January 1967, was successful enough that Creator/{{ABC}} renewed it that fall.
* ''Series/ItTakesAThief1968'', which premiered in January 1968 and lasted for three seasons.
* ''Series/{{Titus}}'' was a mid-season show
* ''Series/{{Coach}}''
* The original run of ''{{Futurama}}'' on Fox started out with midseason premiere.
* The Fox Network premiered in midseason, and as a result several of its more notable early shows such as ''MarriedWithChildren'', ''Series/TwentyOneJumpStreet'', and ''TheTraceyUllmanShow'' did as well.
* ''Series/HappyDays'' as well as its spinoff, ''Series/LaverneAndShirley''
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