Adaptational Sexuality

Elements of a character changing when a work is adapted from one medium to another is an extremely common occurence. Nice Guys might turn into Jerkasses, platonic friends might become love interests, an ally might become an enemy, etc.

One of the most controversial ways of changing a character (much like a Race Lift, and for similar reasons) is to alter their sexuality. This could mean making a gay character straight, giving a love interest to someone described as asexual, making a straight person gay or bisexual, or any combination or variation of the above.

Sometimes a form of Bowlderization, when the change is made to appease Moral Guardians or to avoid controversy. Compare Hide Your Lesbians. Not to be confused with Situational Sexuality.

NOTE: If a character (most importantly if s/he is based on a Real Life person) is merely speculated to have a certain sexuality and a depiction does not follow that, it does not count as this trope, even if said speculation has been generally accepted as fact through Pop Cultural Osmosis.

Anime and Manga

 * Sailor Moon:
 * In the manga, Kunzite and Zoisite's sexuality was never addressed but there is a piece of artwork Naoko Takeuchi made whilst hashing out plot points that were eventually dropped that shows Zoisite and Sailor Mercury and Kunzite and Sailor Venus embracing. In the anime however Kunzite and Zoisite are Yaoi Guys (and in the dub "Zoycite" is a woman).
 * Also Fisheye was never into guys in the manga, again showing romantic interest in Sailor Mercury, but chased men in the anime and once more became female in the dub.

Comic Books

 * Colossus of X-Men fame is straight in the 616 universe, but gay in the Ultimate Universe and in a relationship with Northstar, who's gay in both continuities.

Fan Works

 * A Very Potter Musical has the Scarf of Sexual Preference in addition to the Sorting Hat. Scarfy declares Harry to be metrosexual and Ron to be bicurious.
 * This is pretty much the point of Slash Fic.
 * In Dragon Ball Abridged Zarbon is so camp that he can't seem to say three words without using some sort of Double Entendre

Film

 * The gay, unnamed protagonist of Truman Capote's novella Breakfast at Tiffany's (whom Holly calls by her brother's name, 'Fred') becomes the film's straight love interest Paul. Famously referenced in Seinfeld, when George's attempt to bluff through a book club meeting, having only seen the film, fails spectacularly when his girlfriend has to tell him, "George... Fred's gay."
 * In Tennessee Williams' 1955 play Cat on a Hot Tin Roof, Brick's friend Skipper killed himself after drunkenly confessing his love, and Brick's own feelings are rather violently conflicted and ambiguous. The 1958 film strips out this aspect, which some critics have suggested leaves the central conflict of Brick's character somewhat muddled.
 * Another Tennessee Williams example: In the movie of A Streetcar Named Desire, Blanche's story about her ex-husband's suicide changes from homosexuality (as in the play) to "weakness".
 * Shows up from time to time in the James Bond franchise:
 * The film version of From Russia with Love eliminates Rosa Klebb's lesbianism.
 * Pussy Galore's lesbianism is downplayed in the film version of Goldfinger, where she merely tells Bond she is "immune" to his charms.
 * The documentary The Celluloid Closet was supposed to feature a sequence detailing biopics where the subject was known to be gay or bisexual, but was nevertheless portrayed as straight. It was cut due to rights issues. Some of the films meant to be featured were:
 * The Agony and the Ectasy: Charlton Heston denied the film rights because he insisted that his portrayal of the famous sculptor Michaelangelo as straight was historically accurate.
 * Alexander the Great, starring Richard Burton
 * Hans Christian Andersen, starring Danny Kaye (the filmmakers were denied the rights to this because the studio mistakenly thought the documentary would claim that Kaye was gay, rather than Andersen)
 * Night and Day, starring Cary Grant as a straight Cole Porter.
 * The first film adaptation of the play The Children's Hour changed the story of two teachers having their lives ruined due to rumors that they are having a lesbian affair to rumors that one of them slept with the others' fiance. This is because the Hays Code outlawed even the slightest hint of homosexuality. Even the title had to be changed (to "These Three") because the stage play was so well known as a work that dealt with lesbianism.
 * The Color Purple was criticized for not including the lesbian relationships detailed in the book.
 * Similarly, Fried Green Tomatoes portrayed the relationship between Ruth and Idgie (which is quite clearly a lesbian union in the book) as just friends, with maybe a hint of Les Yay.
 * The film adaptation of David Gerrold's autobiographical novel Martian Child had the openly gay Gerrold played as straight by John Cusack, giving him Amanda Peet to flirt with.
 * In the film adaptation of Tinker Tailor Soldier Spy, is portrayed as gay instead of straight (as in the novel and miniseries).
 * Mind you, this is relevant to anything for all of six seconds.
 * In Rope (the original play) Brandon, Philip and Rupert were explicitly gay. In Alfred Hitchcock's film adaptation (which was made in 1948) it was reduced to subtext between Brandon and Rupert with Brandon also referring to a past relationship with Janet implying he's possibly bisexual.

Literature

 * Imoen in the Baldur's Gate novel.

Live-Action TV

 * Chuck Bass of Gossip Girl is a Depraved Bisexual in the books, but is a straight Casanova in the TV series.
 * The NBC sitcom Love, Sidney made waves when it was first announced, as it would be the first major television show to feature an openly gay main character. However, the show later faced criticism from the gay community because aside from some very subtle Subtext, Sidney's sexuality was never mentioned outside of the pilot.
 * Recent adaptions of Miss Marple and Poirot has some of the exclusively straight cast members turn gay, for example in Three Little Pigs and A Murder Is Announced.
 * Irene Adler is straight in the original Sherlock Holmes canon, but in Sherlock she is a lesbian, or at least bisexual (but only in the sense If It's You It's Okay regarding Sherlock).
 * Xaro Xhoan Daxos, a Qartheen merchant prince from A Song of Ice and Fire is gay, particularly being interested in young boys. Despite claiming to be in love with Daenerys and proposing several times to her, she can see right through him. The TV series, Game of Thrones, made him straight, and a widower. Then again, Xaro could just be a very good liar.
 * In Pretty Little Liars, Emily Fields went from bisexual in the books to a lesbian in the television series, likely to avoid the Unfortunate Implications of the former, where she.

Theatre

 * For the stage adaptation of High School Musical, Ryan was made gay.