Sleeper Hit

""At that time, no one knew that this small work called Gundam was to become a legendary anime, shaking the very foundation of Japan.""

- Gundam Sousei

Any work that becomes an unexpected success upon its release, usually through word of mouth. Either the work slipped under the fandom and critics' radar during production, it was dismissed as crap outright based just on previews, or the company/publisher didn't have much faith on it and neglected its promotion, yet it managed to get sizable box offices or sales. It might make an impact on the fandom collective and become a Cult Classic, or be a matter of Quality by Popular Vote and be forgotten quickly: the point being, exceeding expectations.

It may start a Cash Cow Franchise, and spawn cases of Follow the Leader. It might even start a whole new genre.

Supertrope of And You Thought It Would Fail, where the work is actively derided before release and still ends up being a hit. Compare to Ensemble Darkhorse, when a character in a show/film/etc. becomes unexpectedly popular. If it takes longer than just its initial release to become popular, then it has been Vindicated by History instead.

Contrast Acclaimed Flop.

Anime and Manga

 * K-ON! went from an unknown Yonkoma to a marketing juggernaut when it was adapted into a Twelve-Episode Anime by Kyoto Animation.
 * Something similar happened when Kyoto Animation adapted the Suzumiya Haruhi Light Novels, which had limited underground success up to that point.
 * Gundam, as noted in Gundam Sousei and in the page quote.
 * Hear now the tale of Elfen Lied, a show that was so drenched in blood and nudity that even in Japan it could only air on satellite TV. It was cancelled after one season...and purely by word of mouth, nearly every anime club in America heard about it and it became one of the top-selling anime of 2005, much to everyone's surprise (but too late to get it Uncancelled in Japan).
 * Tiger and Bunny. According to recent articles, T&B was an unexpected success in both ratings and DVD/BD sales — and this has put a lot of pressure on Sunrise's next projects.
 * Shingeki no Kyojin. The mangaka originally sent the manuscript to Shonen Jump, but was rejected. Then, he proceed to sent it to Bessatsu Shonen Magazine, an monthly offshoot of Weekly Shonen Magazine. It was a new mag with their only real hit being xxxHolic, which wasn't even the original mag where it was published, it was just being moved there in 2010 from Young Magazine, a seinen magazine. Now, the manga is one of the best selling shounen manga in Japan, surpassing Bleach. See here.

Film
"Mark Hamill: We didn't even have a poster. *Beat* There was no poster!"
 * A really notorious case: Star Wars. It's hard to believe now, but the movie was expected to tank, hard. So much that it only opened in 37 theaters. Killer word of mouth convinced Twentieth Century Fox to give it a proper release.


 * Pirates of the Caribbean: Curse of the Black Pearl became this when everyone got a good look at Captain Jack Sparrow. Before the film's release, everyone expected it to do horribly because it was based (however loosely) on a theme park ride, not to mention the fact that pirate movies almost always end up being huge box-office bombs.
 * My Big Fat Greek Wedding started off slow, but eventually grossed nearly $250 million on a $5 million budget. It also holds the world record for highest-grossing movie to never have a #1 spot at the box office.
 * The Ring's success by word-of-mouth caused the Japanese horror remake craze back in the 00's.
 * Forrest Gump. Before release, it was only expected to be a modest hit at best and had a smaller than usual opening of 1,500 theatres (at the time, 2,000 theatres was the expected release for a big movie). Excellent word of mouth from sneak previews helped make the film a long runner.
 * Blade was not only a sleeper hit, it probably resurrected the comic book movie genre after Batman and Robin killed it. When Blade came out in 1998 it was thought to be a niche, genre-bending action/horror flick, and in fact the advertising for the film never even mentioned it was a comic-based movie. But all of the elements came together under Wesley Snipes' steely performance, and word of mouth made the film into a hit, spawning two sequels and convincing Marvel to pull the X-Men out of some 20 years of Development Hell to get it out two years later. After that, the flood gates opened and comic-book movies have been a staple of the summer action season ever since.
 * When the first Twilight movie went into production, no one realized how big the fanbase was. This is plenty evidenced by the fact that it was produced by an independent film studio, Summit Entertainment, with a then-unknown cast and cheap special effects. As the release approached, however, it became steadily more and more obvious that the books' fangirls were going to turn the movie into a hit and the media quickly picked up on it. This resulted in a weird situation in which essentially a low-budget indie was being being hyped as a blockbuster. Of course, after the first one came out, Summit realized what a profitable franchise they had on their hands and the sequels were budgeted accordingly, hence bigger actors for roles not already cast and better effects.
 * Before it became a success, the idea that women alone could turn a movie into a blockbuster hit was considered so unthinkable that, when Paramount (having apparently learned nothing from James Cameron) was planning on adapting Twilight, they tried to make it far more action-heavy (basically, a high school version of Underworld or Blade) in an effort to attract the male moviegoers that they thought were necessary. Their plans were vetoed by Stephenie Meyer, leading to the far more faithful adaptation by Summit. Whether this was a good thing or a bad thing depends on the person.
 * Paranormal Activity was picked up by Steven Spielberg after seeing a screener copy in 2007 with the intent to remake the film. After two years on the shelf, Paramount canceled the remake and released the original in a few markets as a midnight movie. After excellent word of mouth and demand for more showings, the studio first allowed it to be shown all day and then went wide in the fourth week after reaching the Top 5 in its third week (doing so in just 160 theatres, a record for the fewest theatres for a film to reach the Top 5). The film grossed over $100 million and has spawned two sequels to date.
 * The first Scream movie was initially dismissed as yet another entry into the beaten-like-a-dead-horse slasher genre, and it made only $6 million on its opening weekend. Word of mouth eventually pushed its theatrical take to $103 million, guaranteeing it three sequels and a wave of copycats. Today, Scream is regarded as a classic horror film.
 * The Bourne Identity had tested horribly for Universal and its Summer 2001 release date was pushed back in order to do extensive reshoots on the film. When it opened, it was expected to flop against rival studio tentpole films Scooby Doo and Windtalkers. Then reviews and word-of-mouth managed to be surprisingly good and became a long runner in theatres, grossing over $100 million in the process. Two even better sequels were later released and a third is coming out in 2012.
 * Babe was a $30 million Australian/US co-production with no stars and a Talking Animal lead that wasn't expected to make its budget back in the summer of 1995. After a decent $9 million opening, near-unanimous critical and audience acclaim got to finish with a $64 million gross and an additional $190 million overseas. The film also got seven Academy Award nominations (winning for Best Visual Effects), a sequel and a long life on VHS and DVD.
 * How to Train Your Dragon started out in first place, but was quickly knocked down after its disappointing premiere weekend. Word of mouth took it back to the top in a month.
 * Se7en had tested badly with audiences and was slotted into the dumping ground of September against the higher-publicized Showgirls with the hope that the film's star power would allow it to break even. Then the critics responded in praise and with audiences agreeing, the film managed to spend four weeks at the top spot. The film went on to gross $327 million worldwide and launched David Fincher's directing career.
 * Austin Powers: International Man of Mystery was considered a throwaway project for New Line Cinema as Mike Myers had not had a successful project post-Saturday Night Live and the film had the worst test screenings in the history of the studio. Expected to die quickly in the heat of the Summer 1997 movies (such as The Lost World: Jurassic Park and The Fifth Element), the film opened decently but kept on going to a final gross in the US of $50 million. But when it hit video, it started a phenomenon that led it to be the most rented movie in 1997 (and still in the Top 10 one year later) and two sequels (with a third in the works) have been made since.
 * Boyz N the Hood was a low-budget urban film that was only intended to be given a small release until two events happened: 1. The film premiering to mass acclaim at the Cannes Film Festival, and 2. Columbia's big Summer 1991 film Radio Flyer getting pushed back due to reshoots, which led Columbia to slot the small production it is place. Even against strong blockbusters Terminator 2: Judgment Day and Robin Hood: Prince of Thieves and violence breaking out at some screenings, the film managed to gross over $50 million, made director John Singleton the youngest Best Director nominee in the history of the Academy Awards, launched the film careers of Ice Cube and Cuba Gooding Jr. and almost single-handedly launched the African-American film industry in the 1990's.
 * Bonnie and Clyde. Jack Warner regretted his decision to put the film into production the moment he read the script, as he felt that the audience wouldn't cheer for the outlaws. Warner Bros had so little faith in the film that they tried to bury it with a release in the doldrums of August 1967, and offered star and producer Warren Beatty 40% of the gross instead of a minimal fee. Despite a glowing reception at the Montreal Film Festival, it received mixed reviews from American critics—while Roger Ebert gave it four stars, many others were put off by its juxtaposition of comedy and (for the time) gratuitous violence.
 * Young Baby Boomers, however, loved it, turning it into a blockbuster and a pop culture sensation that was nominated for ten Oscars (winning two). Beatty became a very wealthy man as a result of his 40% gross, allowing him to do pretty much anything he wanted, while Faye Dunaway became one of the hottest leading ladies in Hollywood. Time magazine, which originally panned the film, featured it on its cover that December. The New York Times even fired its staff critic Bosley Crowther over his panning of the film, feeling him to be out of touch with the modern movie-going public, and replaced him with Pauline Kael, who had praised the film in an op-ed in The New Yorker. Now, it's recognized as one of the fundamental films of the New Hollywood era.
 * Sucker Punch has been stated multiple times that this is a case, it took a year to catch on and find its fan base (though its box office barely recouped the film's budget).
 * While The Hunger Games was the adaptation of a somewhat successful book, no one expected the third best opening weekend over, or that in three weeks it would pass the $300 million mark (outgrossing all Twilight and all but two Harry Potter films).
 * The Denzel Washington/Ryan Reynolds film Safe House was released in the January/February dumping ground and wasn't expected to do much business, but surprisingly the film stayed in theaters for 3 months and made well over 200 million.
 * The film adaption of Think Like A Man was projected at a 15 million opening, to the shock of everyone, the opening weekend tally was 30 million, double what analysts predicted(analysts are rarely ever this off the mark) mostly thanks to positive word of mouth from preview screenings, not only that, but it opened up at number #1 at the box-office, finally knocking Hunger Games down from it's #1 spot that it had held for 4 weeks straight.
 * Opening against Apollo13, Clueless managed to make back it's budget several times over and received critical acclaim.
 * There's Something About Mary wasn't a huge hit at first and only got a small release, but positive word of mouth shot it to the top of the box-office on it's 8th week of release, making back it's 23 million dollar budget more then 15 times over, as well as catapaulting Ben Stiller and Cameron Diaz into the limelight.
 * Crocodile Dundee was only expected to be a modest hit in the U.S., but it ended earning over 300 million and becoming the second-highest grossing film of 1986(only behind Top Gun)

Literature

 * The Fountainhead.
 * Harry Potter.
 * Pratchett's first few Discworld books were small, fantasy parodies. Now, the Discworld series is one of the biggest and most popular pieces of modern fantasy literature.
 * Percy Jackson and The Olympians started out as this because of Harry Potter, which itself was a sleeper hit in it's first years of publication. While the Percy Jackson books are wildly popular now, The Lightning Thief came out the same year as the sixth Harry Potter book, which vastly over shadowed almost all other young adult fiction releases that same year. Because of the release and success of Harry Potter, and the somewhat similar premises of the two series (young boy finds out he has cool powers and goes to a place where others are like him), The Lightning Thief was cast aside as another young adult fiction trying to play off of Harry Potter's success. Word of mouth quickly spread about the Percy Jackson series after the second book came out, because readers started to realize that the two series actually had little in common with each other, and Percy Jackson is now one of the top selling series in the country.

Live Action TV

 * NCIS was largely ignored as simply another CBS crime procedural early in its run and had fairly middling ratings. It eventually became a top five show and now has its own spinoff.
 * Would you believe it if someone told you the Power Rangers fit this trope? Haim Saban spent the better part of a decade looking for a network, be it broadcast or cable, to accept his concept of an Trans Atlantic Equivalent of Super Sentai. No one would accept until Margaret Loesch, then head of the FOX Kids Network gave him the go-ahead. Everyone at Fox thought Loesch had lost it, and wanted the show cancelled before airing even one episode! Luckily, Loesch's faith paid off with an smash hit the likes of which had not been seen since Teenage Mutant Ninja Turtles.
 * The X-Files was a classic example of this. When Chris Carter pitched the idea to Fox, it was initially rejected. When he fleshed it out and pitched it again a few weeks later, they reluctantly took it on. They were unsure about the idea of having a show centered around the paranormal and were not happy with the casting; they wanted someone more more established and traditionally attractive to play Scully. Gillian Anderson was a theater veteran but mentioned later that the X-Files pilot was only her second time in front of the camera. The pilot was well-received by those who watched it (not many) and by critics, but the ratings for the first and second season were rock bottom.

However, it was the increasing popularity of the internet in the 1990s that really saw it take off; The New York Times reported the the show was likely one of the first shows to see audience growth influenced by the internet. The show had its own forums, discussion groups, fan pages and Fan Fiction far before it became commonplace to do so with a show. By season six, The X-Files was Fox's highest-rated show. Its popularity led to Executive Meddling coupled with The Chris Carter Effect and spelled the show's downfall: by its final season, ratings were about where they were for the first and second season. However, the show went on to inspire and influence other shows of the time and subsequent shows (many cult classics in their own right), including Lost, Buffy the Vampire Slayer, Torchwood, Eleventh Hour, Alias, Bones, and most notably Fringe (criticized by many X-Philes as being a rip-off of the original).

Music

 * "Creep" by Radiohead initially received very little airplay upon release in 1992. It wasn't until months later in 1993 that it became an international success that it was re-released in the UK and became a top 40 hit.
 * This seemed to assure that the band would be a one-hit wonder until they released OK Computer.
 * The band Temple of the Dog was formed to record an album mourning the death of Mother Love Bone singer Andrew Wood. The album got little notice when it was released in 1991, but a year later it got some media attention when some of the members had success in a couple other bands you may have heard of.
 * Kaya Rosenthal's song "Can't Get You Out of My Mind" was released to radio stations in 2010, but it got barely any airplay, and the video for the song only had a couple thousand views on YouTube. Fast forward seven months to the release of labelmate Rebecca Black's song "Friday". Suddenly "Can't Get You Out of My Mind" became very popular, and now the video for the song has over three million views on YouTube.
 * Nicki Minaj's album Pink Friday. It got fanfare when it was released, but it was completely overshadowed by the hype for Kanye West's My Beautiful Dark Twisted Fantasy. Its competitors (including Kanye's album) fell, but Pink Friday kept selling, and it reached #1 on the Billboard 200 in its 11th week of release.
 * Hard though it may be to believe, XL Recordings (an indie label) only had moderate expectations for the 21 album by Adele, whose first album had done well enough, but was perceived as being just another Amy Winehouse copycat. The album ended up doing much better in Britain than they had hoped (helped along by Adele's show-stealing performance at the BRIT Awards) and it certainly exceeded expectations for America.

Tabletop Games

 * Magic: The Gathering was shopped around for a while until a little company called Wizards of the Coast, whose only call to fame was being the holder of the Ars Magica RPG franchise, decided to give it a go.
 * Amusingly, Magic itself is known to have Sleeper Hit cards.

Video Games

 * Demon's Souls. As ball-achingly hard as the game is, it proved to be a hit with both players and critics, garnering several "Game of the Year" awards in 2009 and possibly convincing Atlus and From Software to extend the life of its online servers well beyond its planned six-month period.
 * Katamari Damacy. It got initial moderate, but still not-as-expected success in Japan. After numerous positive reviews, the sales of the game kept gradually increasing, especially when it came to North America.
 * Portal was intended as a small bonus to the Orange Box compilation, but became an instant cult classic and the Ensemble Darkhorse of the Orange Box. To put things in perspective, the other games on the Orange Box included Half-Life 2 and its episodes (Including what was the much-anticipated at the time Episode 2) and the much-anticipated Team Fortress 2. That package sold altogether for 50 US dollars at launch. Portal 2 sold for the same price and was still a hit. A Gaiden Game (side story game) developed by ten people as a follow on to a freeware game, was put on The Orange Box with little fanfare. Fans ate it up, the critics loved it, it sold quickly when released as a stand alone, it has inspired a massive sequel, and it became a Fountain of Memes.
 * Touhou. One man making his own Shoot'Em Up games has become one of the best known Bullet Hell series around.
 * Like Star Wars, it's hard to believe that Pokémon was ever a sleeper. When it was first released over in Japan, the Game Boy was on its last legs. Despite this, Pokémon Red and Blue kept selling, spurred by rumors of a hidden 151st Pokémon. By the time it reached the US, the juggernaut was in full swing.
 * Still, it took a while to catch on in the US, as Western divisions of Nintendo had dismissed it as a Widget Game until its popularity had exploded in Japan. Gamers used to complain that Pokémon Red and Blue weren't in color, unaware that they came out only one month ahead of Game Boy Color.
 * Minecraft, and how! This game is outselling many others by word of mouth alone, and it was made by one person.
 * Scribblenauts. While developers 5th Cell were not unknown at the time, having already made the well-liked Drawn to Life and Locks Quest, they weren't considered hugely big contenders in the game scene, and Scribblenauts premiered with little fanfare. The concept was enticing, but didn't make any waves... Until E3 2009, when the greater game journalism public got their hands on the game. Cue explosion.
 * Both System Shock games.
 * The first Tokimeki Memorial game was this: a low-profile game, it became a surprise massive hit thanks to word of mouth. It soon became a long and successful Cash Cow Franchise for Konami, and lots of companies tried to cash on the non-H Dating Sim genre it created with varied success.
 * The original Mega Man fell under the radar until positive word of mouth made into Capcom's flagship franchise.
 * Viewtiful Joe.
 * Lunar: The Silver Star was released on the Sega CD and was one of the first Eastern RPGs to hit the States during the 16-bit era. It got so popular they can't stop making remakes.
 * Angry Birds has proven itself to be the little iPhone app that could, having reached the top of the Apple App Store download rankings in over 60 (!!) countries.
 * The World Ends With You had little to no advertising for its US release, but word of mouth made it the top selling Nintendo DS game its first week in America. The only reason it didn't stay that way for the next few was because the stores literally ran out of copies to sell almost overnight and would be back-ordered for quite a while. Even today it still gets rather high on Amazon's best selling DS games, coming after new releases and Nintendo's Cash Cow Franchises in sort by best selling.
 * The Witcher was a PC-only single player CRPG released in 2007 by a development studio largely unknown outside eastern Europe, based off a fantasy setting almost unheard of in the English-speaking world. It proceeded to sell over a million copies in its first year of release, with its sequel reaching that number in under six months.
 * The original Super Smash Bros. started a side project by Masahiro Sakurai that Satoru Iwata allowed him to do on the weekends at HAL Laboratory. Eventually Iwata became interested in this "King of the Hill"-like fighter, and the company asked Nintendo if they could use some of their characters. Nintendo was iffy on the entire thing: keeping the budget on the game incredibly small and planning on a Japan-only release. Despite little promotion, the game took off in Japan and was brought to the United States and Europe later that year, becoming a Killer App for the Nintendo 64, along with its two sequels for their respective consoles.
 * The Nintendo Entertainment System, and by proxy Super Mario Bros. The Great Video Game Crash of 1983 made console gaming a joke in America, and as such, retailers were not real eager to stock their shelves with any consoles. This made it necessary to sell the NES with R.O.B. so that people would buy it for the toy robot but keep it for the games. Mario had seen some moderate success with Donkey Kong and Mario Bros, but not on a scale that was terribly notable. But very impressive word-of-mouth for Super Mario Bros, coupled with the game being bundled with the NES, made both smash hits.
 * Mortal Kombat was made simply to fill a hole in Midway Games's arcade schedule. A four-man team was given 10 months to churn out a fighting game and pretty much gave them free reign to do what they wanted since it was a small project. The team turned it into one big Rule of Cool game that gave Midway its signature, money-making franchise and cut way more into Street Fighter II's marketshare than they could have imagined.
 * No More Heroes became this in 2007; despite the fact it sold terribly in Japan, it managed to sell decently in other territories, and now has a rather sizable fanbase and an equally successful sequel. One could chalk it up to the fact that its one of the very few Ultra Super Death Gore Fest Chainsawer 3000 games on the Wii, and that its pedigree was a cult classic.
 * The original Final Fantasy. It was supposed to be Square's Swan Song title, but instead managed to fish the dwindling developer out from near-bankruptcy and helped turned it into the giant it is today.
 * Edmund McMillen didn't hold a lot of hope in The Binding of Isaac, mostly because he thought it would be too difficult and / or too disturbing for most people to get into it, so it was quite a surprise for him when it managed to the half million of purchases, and in a relatively short time! He originally planned this game as a side project between Super Meat Boy and another game.
 * Xenoblade Chronicles is probably one of the most notorious examples in recent memory. The game was outright snubbed for an American release despite previous news that it would be released there. However, the game got itself a very vocal fan base right from the start, since it was the new JRPG by the creators of the cult classics Xenogears and Xenosaga. An entire web campaign (Operation Rainfall) was started to get the game released in Western countries, but Nintendo of America didn't listen. Nintendo of Europe and Australia, however, brought it over to their respective continents. With little advertising and very limited units (understandable, since JRPG's had fallen from grace), the game was a surprise success, garnering positive reviews and rather good sales. Since then, the game has been announced for an American release, and other Op. Rainfall games The Last Story and Pandoras Tower are getting expanded ad campaigns and an American release for the former.

Western Animation

 * Let's be honest, no one expected My Little Pony Friendship Is Magic to be the hit that it is.
 * Or Regular Show.
 * Adventure Time started out as a short produced for Nickelodeon's Random! Cartoons show, which was pre-screened and then leaked onto the internet, where it gained a massive amount of popularity in 2007. People who liked the short were already begging for it to be made into a series then. It didn't matter which critics didn't like it, the show had a fanbase three years before it even aired.
 * Recess was originally just going to be another Disney animated series. But due to excellent word of mouth, positive critical reception, and a huge Periphery Demographic, it ended up outliving most of the other shows on the One Saturday Morning block, had a very successful movie, and was rerun to death on every Disney station.