Genre Adultery

"Kurt Cobain: "It's not going to be about food, is it?" Al: "No, it's going to be about how no one understands your lyrics.""

- "Weird Al" Yankovic asking for permission to parody Nirvana's "Smells Like Teen Spirit"

So you've just bought a new novel from your favorite author. You've read every book thus far, and are outright giddy about this new book. You pop onto your couch and open it up, and... hey! This doesn't look like anything before it from this author, or, as you will learn later, after it. You've discovered the outlier; the author has committed Genre Adultery. Perhaps the sausage machine producer of crime novels has shifted from a light hearted Great Detective to a hard boiled Dirty Cop or even as extreme as writing in a completely different genre, but not often. Keep in mind that just because it's different doesn't mean it's bad.

This trope doesn't just exclusively apply to literature, but it's certainly an obvious way to phrase it. Music albums, movie sequels, even tv shows can be a radical departure from the creator's norm. The only thing that matters is that the new style is never return to again in such a manner which is what distinguished it from He Also Did, its Supertrope.

For musicians it may lead to a Black Sheep Hit and may occur for when trying for New Sound Albums but never return to that sound. See also: Playing Against Type and Genre Shift. compare with Genre Roulette

Anime & Manga

 * Special Duty Combat Unit Shinesman was quite a departure from Kaimu Tachibana's usual work.
 * Naoki Urasawa is responsible for Monster, Twentieth Century Boys, and... Yawara a Fashionable Judo Girl.
 * Yuu Watase went from Fushigi Yuugi and Absolute Boyfriend to Sakura Gari...
 * The mangaka who did The Electric Tale of Pikachu typically wrote hentai.
 * The author of Angel Densetsu, a very Genre Savvy humorous story is also the author of the bleak and gorey fantasy series Claymore. Oddly, the two do have a bit of a connection, as some characters are visual expies of each other.

Fanfiction

 * Eliezer Yudkowsky is most well-known for the blog Less Wrong, as well as having written Three Worlds Collide and the fanfic Harry Potter and The Methods of Rationality, which are more or less Author Tracts about his view of rationality. He also wrote Peggy Susie, which is a parody of The Terminator using Calvin and Hobbes characters, which contains very little philosophical speculation.
 * superstarultra is an author well-known in the Haruhi Suzumiya fandom for his Crack Fics. He is also in the process of writing a horror-story collection. Then again, perhaps this is to be expected.

Film

 * Mel Brooks produced The Elephant Man but had his name removed so that nobody thought it was a comedy.
 * He also produced David Cronenberg's remake of The Fly.
 * Busby Berkeley, best known for his lavish musical numbers, directed a crime drama remake called They Made Me a Criminal in 1939. Warner Brothers gave him the oddball project in an attempt to keep him occupied so he wouldn't leave the studio; it didn't work.
 * Horror director Wes Craven directed Music of the Heart a based on a true story drama starring Meryl Streep about a music teacher in a school in Harlem.
 * What's more, this film was actually Craven's pet project, and he only directed Scream 3 so he would be financed and allowed to direct Music of the Heart
 * He also directed a segment of Paris Je T'aime.
 * Bob Clark directed several notable horror films in the early '70s, including Children Shouldn't Play With Dead Things, Deathdream, and the groundbreaking Black Christmas. Then he abandoned horror, directed the teen sex comedy Porky's, and spent the last 20 years of his career making more family-friendly films such as A Christmas Story and Baby Geniuses.

Literature
"My last three books were set in the world of business, and suddenly I'm writing about bodyworkers and high lamas? What's my dad going to think? Will the Wall Street Journal ever talk to me again?"
 * "The Monkey's Paw" was the one and only horror story by a fellow who mostly wrote about sailors.
 * While it's in the sci-fi genre like most of his stories, Good Night, Mr. James by Clifford D. Simak has been described by the author himself as unique ? it's much darker in tone than most of his work, and has a Shoot the Shaggy Dog ending.
 * John Grisham usually writes legal fiction. Only four aren't of this genre, and one of them is Skipping Christmas. A Christmas Special, of all things. A Painted House, a coming-of-age story in Depression-era Arkansas, is another.
 * The Big U, a college campus satire novel by none other than Neal Stephenson, science-fiction writer and author of Snow Crash.
 * He does not like the book, and discontinued publishing for a while. Then people started paying hundreds of dollars for old copies of it, and he had it republished, saying that "the only thing worse than people reading the book was paying that much to read it." To be fair, it was his first novel.
 * Elmore Leonard's short novel Touch seems glaringly out of place as a supernatural thriller compared with the rest of his collection of crime novels.
 * Ian Fleming's The Spy Who Loved Me was the only James Bond novel written from a woman's point of view. Probably why he didn't like it and put in the film deal that an adaptation of that book should be In Name Only.
 * Ian Fleming also wrote Chitty Chitty Bang Bang. (The film version was scripted by Roald Dahl.)
 * Joanna Russ, one of the angriest feminist science fiction writers ever, wrote a children's book (Kittatinny).
 * Roger Zelazny is primarily known for writing science fiction and fantasy, but he also co-wrote (with Gerald Hausman) the novel Wilderness, a straightforward story of frontier survival.
 * James Patterson is so well known for writing thrillers that when he wrote Suzanne's Diary for Nicholas, a romance novel, the television commercial even lampshaded the trope by saying "By James Patterson. Yes, James Patterson."
 * H.P. Lovecraft wrote a comic short story Sweet Ermengarde, a parody of romantic melodrama.
 * Robert W. Chambers, the author of the supremely creepy The Repairer of Reputations and The Yellow Sign, mostly wrote light, fluffy romantic comedy stories. A reader looking for more weirdness is likely to be very disappointed.
 * Orson Scott Card, writer of Ender's Game and other science fiction and fantasy stories, also wrote a series of soap-opera-ish stories about women in the Bible.
 * Stephen Donaldson is famous for writing speculative fiction: Thomas Covenant, Mordant's Need, the Gap novels. He is not at all famous for his series of detective novels entitled The Man Who [did something]. (Interestingly, he's in the habit of writing a new detective story after completing a series of fantasy novels: it seems to be how he winds down.)
 * Suspense novelist Dean R. Koontz surprised his fan base with a sweet-natured illustrated children's book called "Oddkins" in 1989.
 * He then followed it with the illustrated kids' Christmas books "Santa's Twin," and its sequel "Robot Santa," though those were much darker in tone.
 * After writing the novels Bombardiers, a novel about Wall Street greed; and The First 20 Million Is Always the Hardest, which is about Silicon Valley; Po Bronson wrote The Nudist on the Late Shift, a non-fiction book that was also about Silicon Valley. Then he wrote What Should I Do With My Life? and had this to say:


 * Steve Martini started off writing courtroom dramas with twist endings. His series character suddenly found himself thrust into the world of international assassins and intrigue and has stopped a few weapons of mass destruction.

Music

 * Lights, a Canadian Synth Pop artist, released an acoustic EP with re-workings of some of her previous songs, as well as a brand new song and a light re-imagining of an old punk song.
 * Remain in Light by Talking Heads.
 * Pet Sounds by The Beach Boys.
 * Pinkerton by Weezer. Might be a bit premature, as the band hasn't broke up yet.
 * The Rolling Stones album Their Satanic Majesties Request. Despite the title it is surprisingly psychedelic. The jury is out on its good status.
 * Elvis Costello's The Juliet Letters. This was a collection of songs based on letters written to Juliet (who's considered to be a help to the lovelorn). The album was done as a collaboration with the Brodsky String Quartet who had much more collaboration into the writing process than was usual on an Elvis Costello album.
 * The Queen album Hot Space is full of disco songs, a departure from their usual rock music. After Hot Space they never touched disco again.
 * The Melvins have had several album-length left turns, but possibly the most surprising is The Bootlicker: while their sound usually involves sludgy walls of feedback, this album features absolutely no guitar distortion. The actual content doesn't get any lighter and softer, but the arrangements bring to mind Tom Waits and krautrock more than they do grunge or stoner metal.
 * The Butthole Surfers' Weird Revolution, which is much more electronica-influenced than anything they'd previously done. It may have been an attempt to roll with their popular Black Sheep Hit "Pepper", although it was actually preceded by a couple of electronic-based soundtrack contributions, along with the similar but much more experimental After The Astronaut, which got shelved after promo copies got scathing reviews.
 * Brian Eno noted that he wanted the first reaction of U2 fans who bought Achtung Baby to think that either their stereos were broken or that they accidentally purchased the wrong album.
 * Although it was recorded as a joke, Anal Cunt's Picnic Of Love is a complete inversion of their trademark style: instead of short grindcore songs with Dead Baby Comedy lyrics and song titles, it consists of 2-3 minute acoustic ballads sung in falsetto, with titles like "I'd Love To Have Your Daughter's Hand In Marriage".
 * Kiss had the disco album Dynasty.
 * Part of the reason for the violent backlash against disco was that this happened with so many artists that it began to appear that disco would engulf everything.
 * Ween's 12 Golden Country Greats was a country album, which used veteran country session musicians as a backing band. Though they'd had the odd country-influenced song before and since, it was still a pretty unexpected turn, especially because they generally played it straight (well, aside from "Piss Up A Rope" and "Mr. Richard Smoker" anyway).
 * "Anniversary" by Voltaire is a straight love song, with no references to death, goths, evil, or Sci Fi shows.
 * His later country album may also count.
 * Joy Electric is Synth Pop, as the name implies. The album Unelectric featured acoustic arrangements of prior songs.
 * Pete Shelley, frontman of the punk group The Buzzcocks, was regarded by fans as having invoked this trope in 1981 with the synthpop album Homosapien.
 * Most Pat Benatar albums are album-oriented rock and roll... except True Love, which is jump blues.
 * Alice In Chains' Sap and Jar Of Flies EPs. The albums surrounding them can best be described as grunge metal, but these eps are acoustic alternative rock.
 * Pretty much every Captain Beefheart album, especially Unconditionally Guaranteed.
 * Country Music singer Alan Jackson did a very blues-pop oriented album, Like Red on a Rose, in 2006. It was also the only album on which he did not work with producer Keith Stegall, instead choosing bluegrass pioneer Alison Krauss. Also, despite having written maybe 75% of his own songs, his only contribution as a writer on Like Red on a Rose was "A Woman's Love", a re-recording of a track from his 1999 album High Mileage.
 * This is what launched Ludwig von Beethoven's fame, for when got deaf, he moved out of his classical style and shifted music towards the romantic period.

Webcomics

 * David Herbert's Tnemrot is a serious manga story, which seems weird, since Living With Insanity is all about craziness and T&A.