[[caption-width-right:278:As his mustache demonstrates, he liked twist endings.]]

William Sydney Porter, PenName O. Henry, is an American writer of chiefly short fiction (the most famous piece being "Literature/TheGiftOfTheMagi") and one novel (''Cabbages and Kings''). His stories are famous for their [[MandatoryTwistEnding Mandatory Twist Endings]], warm characterization and wit.

For some inexplicable reason--at least partially having to do with two [[FilmOfTheBook film adaptations]], which are quite good--he is [[GermansLoveDavidHasselhoff most popular in the former USSR republics]], where phrases such as "Bolivar cannot carry double" have become stock quotes.

The "Oh Henry!" candy bar (later associated with Hank Aaron) was partly named in homage to him. (And partly named for a boy who flirted with the girls at the candy factory.)
!!Works by O. Henry with their own trope pages include:

* "Literature/TheGiftOfTheMagi"

!!Other works by O. Henry provide examples of:

* AllJustADream: ''The Roads We Take'', although it is more a case of IronicEcho.
* BananaRepublic: ''Cabbages and Kings'' is the TropeNamer.
* BeleagueredChildhoodFriend: ''After 20 Years''.
* BigApplesauce: A popular setting of many of his stories; the short story collection ''The Four Million'' is set there.
* BrattyHalfPint: Johnny Dorset from ''The Ransom of Red Chief''.
* CantGetInTroubleForNuthin: ''The Cop and the Anthem''.
* ConMan: Jeff Peters and Andy Tucker, protagonists in a cycle of stories.
* {{Cowboy}}: Normally of the Working Cowboy varieties, protagonists in many stories.
* CorruptCorporateExecutive: An early example in "Shark" Dodson from ''The Roads We Take''.
* DomesticAbuse: ''A Harlem Tragedy'', which, despite the title and the subject matter, is a very light-hearted story.
* DownerEnding: Occasionally, for example in ''The Furnished Room'' and ''The Last of the Troubadours''.
* ExasperatedPerp: ''The Ransom of Red Chief''.
* IllGirl: ''The Last Leaf''.
* IneffectualSympatheticVillain: ''The Ransom of Red Chief''.
* LetOffByTheDetective: ''A Retrieved Reformation''.
* LukeIAmYourFather:
* MockMillionaire: ''Transients In Arcadia''; ''The Policeman O'Roon''
* NiceJobBreakingItHero: ''The Last of the Troubadours''.
* NoNameGiven: What the hell does that "O" stand for?
* PityTheKidnapper: ''The Ransom of Red Chief''.
* StupidCrooks: As mentioned immediately above, the kidnappers in "The Ransom of Red Chief." They're dumb enough to kidnap an obviously evil child, and he's such a terror that they end up having to pay his father to take him back.
* ThatManIsDead: ''A Retrieved Reformation'', in a way.
* TomatoSurprise: ''After Twenty Years'' has the revelation that [[spoiler:the main character is an infamous criminal.]]
* TrainJob: ''The Roads We Take''.
* TrickTwist
* VillainProtagonist: Because O. Henry spent time in jail, many of his stories, like ''The Ransom of Red Chief'', focus on (relatively) petty criminals.
* WildWest: Another popular setting; usually limited to Texas ranches.