The vast majority of television shows don't make it very far. Networks order dozens of new series every year, launch the most promising ones in the fall... and almost immediately begin cancelling ones that don't live up to expectations, replacing them with the shows that didn't make the first string of launches, in the hope of eventually getting a schedule of hits. The network model simply isn't generous to shows that don't get off to a healthy start.
But for all the dozens of shows that fail in their first year, there are a few that survive this initial culling, complete their first season, and are renewed for a second. Smooth sailing from now on, right?
Well... not always. Sometimes nobody expected the show to make it, and so the writers and producers pulled out all the stops in the first year, leaving nothing to work with for the next season. Sometimes a show with a novel concept inspires imitators that either pull off the gimmick more skillfully, or are so ubiquitious that viewers become bored with both the original and the knockoffs. Sometimes Executive Meddling is to blame, especially if the second season coincides with a change in network leadership. Sometimes there's no clear cause at all; the show simply ran out of steam, and Seasonal Rot kicked in early. And perhaps most common of all, maybe the network just didn't want to commit to two more seasons of the show. Yes, two more seasons. Very, very few American broadcast network shows are canceled after their third season because a show usually needs about 4 seasons' worth of episodes in order to be viable for off-network syndication, which for producers is often where the real money is. So, if a network looks like it might be thinking about canceling a show after its third season, the studio that produces that show will usually offer the network some sort of incentive to keep it on the air for long enough to reach syndication; as a result, when network programming executives decide whether or not to renew second-season shows, they often do so based on whether they can see having that show on their schedules for another 2 seasons.
In any case, there are a lot of shows that successfully make it through a first season, only to fall victim to a Sophomore Slump and get canceled by the end of a disappointing second season. In the end, these shows are Short-Runners.
Todd VanDerWerff, writing for Vox, has gone into depth on this trope, referring to the second season as a make-or-break point for a TV drama. He argues that this has become especially common for the sort of big, high-concept premises that make up many "prestige" shows in the 2010s, which lend themselves well to great first seasons but are difficult to follow up in the second season, the point where "a TV premise becomes a TV show" and they need to expand the world and supporting characters rather than just rely on the basic premise to pull in viewers. Shows that fail to do so will inevitably be remembered as having only been good for one season, even if they manage to get renewed afterwards.
Note: This only applies to shows that end after their second season. If the show is believed to have declined in quality during the second season, but nevertheless continues for a third season or beyond, that would be a case of Sophomore Slump (if the show improves with its third season), or Jumping the Shark (if despite a third and/or additional seasons, the show does not improve in quality over the second). If quality varies during different seasons, you're dealing with Seasonal Rot.
- The Avengers: Earth's Mightiest Heroes! has a first season bearing arguably some of the greatest pieces of Marvel-adapted animation. In contrast, the second season suffers from having more filler than the first, especially after Jeph Loeb and Man of Action Studios came on as executive producer and creative consultants, respectively. They created so much filler, that subplots the original writers set up earlier went unresolved and/or unexplored by the time the show ended. Their run also saw most of the Avengers get pushed Out of Focus, and Out of Character Moments become more frequent. Plus, the animation in this season sometimes seems cheaper, and the awesome theme song permanently got ditched in favor of recaps of old episodes and a promo for the Avengers movie. The show's low ratings among the target demographic, at least compared to the Periphery Demographic, prevented the green-lighting of a third season.
- The Critic was pulled from ABC after its first season, then made a Channel Hop to Fox for its second. However, this season only lasted three months and proved to be the show's last.
- The Incredible Hulk: The Animated Series was a dark cartoon — its protagonist was a Woobie, Destroyer of Worlds, always on the run, attacked from all sides by hero and villain alike. The Hulk is alone. This trope comes along in season 2, and the earlier introduced character of She-Hulk is now in every episode, making it far more Lighter and Softer. Hulk wasn't even an outcast. This sudden shift in the series' tone led to a swift cancellation.
- Legion of Super-Heroes was heavily retooled due to Executive Meddling in its second season, which ended up being its last.
- Sonic Sat AM, though this was more due to the simultaneous cancellation of all of ABC's then-current lineup in favor of Disney programming (as they had just acquired ABC) than the actual quality of the writing. It has been observed that was an increase in comedy episodes, but the season also delivered a well-received Story Arc.
- The most prominent reason why Whatever Happened to... Robot Jones? never lasted long was because Cartoon Network SOMEHOW thought it was a good idea to air the episode premieres of the second season at 10:30 p.m. and the only other reruns being on Sunday at 4 p.m. Great move, Cartoon Network. REAL great move.
- The second season of The Twisted Tales of Felix the Cat took a budget cut in the animation, attempted to take the series into a more script driven and less weird direction with more emphasis on the Joe Oriolo era of the Felix the Cat series, and the change was not for the betterthe ratings for it tanked even harder than the first seasons underperformance. It only lasted eight episodes before the show was cancelled altogether. Even the production team considered the second season a complete disaster.
- Jimmy Two-Shoes' second season experienced a decline in both animation quality (due to a production change from ToonBoom to Adobe Flash) and writing quality (producing some of the fanbase's most hated episodes and poorly handling its characters, especially Ensemble Darkhorses Heloise and Saffi). There was also the lack of promotion by its international distributor, Disney XD, taking its toll, which ultimately killed the show despite announcements for a third season.
- AfterM*A*S*H was cancelled in the middle of its second season.
- Breaking In had a well-received but extremely short (only seven episodes) first season. Viewing numbers were low but enough fans caused a loud-enough ruckus for Fox to un-cancel it for a second season. Unfortunately, the second season dropped the two of more intriguing characters, brought in two hated replacement characters, had to write out the primary love interest (her actress had been cast in House after the original cancellation), changed the concept from a weekly heist show to office comedy, and neutered the Magnificent Bastard into an ineffectual afterthought. The show couldn't even finish its miraculous second season.
- Car 54, Where are You? went directly up against the second half of The Ed Sullivan Show (Sundays at 8:30) in both of its two seasons.
- CBS originally aired The Good Guys, Bob Denver's first series following Gilligan's Island, on Wednesdays during the 1968-1969 season. The fall of 1969 saw the series moved to the Friday Night Death Slot against The Brady Bunch , and The Good Guys disappeared in January 1970.
- The Monkees was highly appreciated during its first season, providing the Fake Band with three hits and two #1 albums by the season's end. In the second season, the timeslot (Monday at 7:30) stayed the same but its competition became Gunsmoke, and the series' cancellation at the season's end caused the group to go downhill.
- Room For Two, an ABC mid-season replacement in 1992, overperformed in its short first season, ending as one of the top 20 shows on network television. Its second season saw its ratings plummet, though.
- The Ropers, a spin-off of Three's Company, did great as a six-episode tryout on Tuesday nights following its parent show. But once it was moved to Saturday nights for Season 2, the ratings fell and the show limped through the year.
- Time Gentlemen Please, Al Murray's sitcom, got a second season, and was so poorly received that neither full series was released on DVD until 2009.
- I'm Alan Partridge (Series 2) killed the series until it was revived a decade later. The second went overboard on the sitcommy elements, particularly Alan's Ukrainian girlfriend Sonja, and whilst the first one could have you feeling sorry for Alan, the second made him wholly self-centered and unlikeable. The travel tavern in the first series was a much better setting than the caravan, because it allowed Alan to interact with more characters. The second series is certainly watchable, just a step down.
- Sledge Hammer! is an interesting case. It looked as though the show wouldn't survive its first season, so the final episode ended with a nuclear explosion with the cast at ground zero. The ratings were surprisingly up for that episode, so a second season was approved by the network (with the season premiere claiming all future episodes take place five years before the nuke, despite obvious continuity issues that created). However, for the second season, the budget was cut (most shows get a budget increase with a second season), meaning the episodes looked cheaper, and fewer episodes entirely were produced. Even more damaging, ABC put the show up against ratings juggernaut The Cosby Show. The second season would be its last.
- Bracken's World had so bad a first season (1969-1970) that NBC had to change it significantly. Nothing helped — not even with the addition of Leslie Nielsen — and by the end of 1970 the series was history.
- CBS' expensive Prime Time Soap Central Park West was heavily retooled after an under-performing Season 1, missing half the original cast. The retooling only alienated the show's dwindling fanbase, and it was canned at the end of Season 2.
- Dark Angel spent its first season as a fairly gritty and down-to-earth Post Cyber Punk series where the villains were criminals and corrupt authority figures. The second season abandoned that for a Genetically Engineered Creature Of The Week formula and an ongoing plotline involving an Ancient Conspiracy and the heroine being the Chosen One. It did not go over well, and the series was cancelled.
- Joss Whedon's Dollhouse survived its first season but was cancelled at the end of its second. Fans love to argue over whether or not Fox really felt the show deserved a second season, or were just trying to avoid a repeat of the situation with Firefly.
- Gabriel's Fire (1990) was a serious drama starring James Earl Jones as a former police officer, wrongly convicted of murder, who becomes a private detective after his release from prison. In its first season, it won three Emmys (Outstanding Lead Actor in a Drama Series (Jones), Outstanding Supporting Actress (Madge Sinclair), and Outstanding Guest Actor (David Opatoshu)) and an NAACP Image Award. Going into its second season, the show was re-tooled into a Lighter and Softer Dramedy called Pros and Cons. The new version was cancelled after 12 episodes.
- It could have been worse: the original Working Title for season 2 was Bird and Katt.
- Human Target was on the ratings borderline even in its first season, but that season had a solid reputation for its strong action sequences and compelling characterization. With a somewhat surprising renewal for season two came a boatload of Executive Meddling, the introduction of new female characters who ultimately contributed little and took focus off the original trio of Chance, Winston and Guerrero, the firing of composer Bear McCreary in favor of Tim Jones, whose compositions were considered ill-fitting and hollow, and the elimination of any ongoing storylines from the first season. Fans were not impressed and left the series in droves, while casual viewers sensed that the show was most likely being used to fill space until the premiere of The X Factor and also stayed away. Thus, the show was eliminated along with the rest of Fox's drama underperformers from this season (excepting Fringe) in May 2011.
- Joan of Arcadia, thanks to heavy Executive Meddling to make it more marketable to teens, eliminating the premise of Joan rescuing lives and helping her father solve crimes, and centering it around high school drama.
- She Spies started off as a successful Affectionate Parody of the whole Spy Fiction genre (it originally had a production team consisting of veterans of Moonlighting, and made similar use of Fourth Wall abuse). In the second season, the production company changed (to the company that produced Baywatch,) and the show underwent a massive retooling (the only things that remained were the three lead actresses and the general Boxed Crook premise.) The tone shifted from light-hearted parody to straight drama, it became much more of a lukewarm retread of Charlie's Angels, and was cancelled.
- Smash was already a victim of deteriorating ratings and Snark Bait (the term "Hate Watching" was popularized by this show) during its first season. NBC fired creator Theresa Rebeck, replaced her with the show runner from Gossip Girl, and heavily retooled the cast, ditching most of the more infamous scrappies. However, the network also stranded it on Tuesdays in between cycles of The Voice, where its lead-in was the incredibly weak rookie comedy The New Normal. Smash predictably collapsed further in the ratings, and continued to be Snark Bait with critics, but without the same level of cultural awareness from the first season (when it aired behind The Voice). NBC eventually banished it to Saturdays partway through its second season to quietly dispose of what was once believed to be their future franchise drama.
- Although the first season of Space: 1999 faced some criticism for the physical improbability of its setup, it was still well-received for the most part and often compared to 2001: A Space Odyssey. The second season, on the other hand, was an entirely different story, seen by many as one of the most egregious examples of this trope in sci-fi. For its second half, the series was retooled into a Lighter and Softer action series with much less cerebral plots and several characters removed without explanation. These changes went over very poorly with the established fandom and even some of the cast members (especially Martin Landau) and the series was swiftly cancelled soon after.
- Touch is similar to previous Fox series Dollhouse in that it only got two half-length seasons of 13 episodes each, with one first-season episode not even airing during the regular season (it was aired as a bonus in September 2012, six weeks before the intended second-season premiere). Weak ratings for the bonus episode were probably the reason why Fox chose instead to postpone the premiere for nearly four months until it could take over the Friday Night Death Slot following the ending of Fringe, and the new season's ratings were as poor as those of Fringe - a huge shocker, considering it had the strongest debut of Fox's four freshman series of 2011-12. Unlike Fringe, however, Touch sadly didn't have the benefit of a large and devoted fanbase to keep it alive, even with the Darker and Edgier, more Myth Arc-oriented turn the second season took.
- Twin Peaks. David Lynch explicitly stated that he never wanted to bring the Laura Palmer story to a close, preferring to use it as a frame for the sub-plots and span it over several seasons, but ABC didn't think the audience would stick around. As a result, her killer was revealed halfway through Season 2 and the show became nothing but sub-plots. Lynch justifiably backed mostly out of its production to continue with his film career, directing only a few episodes with others directed by filmmakers of various skill levels.
- Most diehard fans of War of the Worlds tend to hold the opinion that the changes from the first to second season (which included the deaths of several major and supporting characters - including the villains of the first season, the world flipping over 20 Minutes into the Future and most of the first-season plot threads dropped in favor of standalone episodes) caused the show's death.
- The Frank Sinatra Show was a musical variety show broadcast on CBS for two seasons from 1950 to 1952. While the first season did well on Saturdays at 9 against Your Show of Shows on NBC, the second one faltered on Tuesdays at 8 against Texaco Star Theater (Milton Berle's show) on NBC and the surprise hit Life is Worth Living on DuMont, which debuted in mid-season. The show's popularity was also hurt by the scandals surrounding Sinatra's affair with Ava Gardner and his musical career being at a low point commercially and artistically (his late Columbia-era output being notorious for gimmicky novelty tunes). note
- The Pat Sajak Show was an attempt by CBS to challenge Johnny Carson that put the host of Wheel of Fortune through massive changes while in late night. It didn't help, and Sajak was yanked off near the end of Season Two.
- The American version of That Was the Week That Was was hit hard with this in its second season, especially because it conflicted with the 1964 Presidential election, and until the election was over it was shown only on a monthly basis. By the time it went back to a weekly program, most of its viewers had switched to its competition, Petticoat Junction and Peyton Place.