O. Henry was the pen name of American writer William Sydney Porter (September 11, 1862–June 5, 1910), whose clever use of twist endings in his stories popularized the term "O. Henry Ending". His middle name at birth was Sidney, not Sydney; he later changed the spelling of his middle name when he first began writing as a journalist in the 1880s.
William Sidney Porter was born in 1862 on a plantation "Worth Place" in Greensboro, North Carolina. When William was three, his mother died from tuberculosis, and he and his father moved to the home of his paternal grandmother.
William was an avid reader, and graduated from his aunt's elementary school in 1876, then enrolled at the Linsey Street High School. In 1879 he started working as a bookkeeper in his uncle's drugstore and in 1881 – at the age of nineteen – he was licensed as a pharmacist.
The Move to Texas
He relocated to Texas in 1882, initially working on a ranch in La Salle County as a sheep herder and ranch hand, then Austin where he took a number of different jobs over the next several years, including pharmacist, draftsman, journalist, and clerk. While in Texas he also learned Spanish.
In 1887 he eloped with Athol Estes, then eighteen years old and from a wealthy family. Her family objected to the match because both she and Porter suffered from tuberculosis. Athol gave birth to a son in 1888, who died shortly after birth, and then a daughter, Margaret, in 1889.
In 1894 Porter started a humorous weekly called The Rolling Stone. Also in 1894, Porter resigned from the First National Bank of Austin where he had worked as a teller, after he was accused of embezzling funds. In 1895, after The Rolling Stone ceased publication, he moved to Houston, where he started writing for the Houston Post. Shortly thereafter, he was arrested for embezzlement in connection with his previous employment in Austin.
Flight and Return
Porter was granted bond, but the day before he was due to stand trial on July 7, 1896, he absconded to New Orleans and later to Honduras. However, in 1897, when he learned that his wife was dying, he returned to the United States and surrendered to the court, pending an appeal.
Athol Estes Porter died July 25, 1897. Porter was found guilty of embezzlement, sentenced to five years jail, and imprisoned April 25, 1898 at the Ohio State Penitentiary. He was released on July 24, 1901 for good behaviour after serving three years.
Origin of Pen Name
Porter published at least twelve stories while in prison to help support his daughter. Not wanting his readers to know he was in jail, he started using the pen name "O. Henry". It is believed that Porter got this name from one of the guards who was named Orrin Henry. However, there is much debate on this issue: one Porter biographer asserts that the name was derived from a girlfriend's cat, which answered to "Oh, Henry!" Guy Davenport, meanwhile, wrote that the name was a condensation of "Ohio Penitentiary". It also could be an abbreviation of the name of French pharmacist, Etienne-Ossian Henry, who is referred to in the U.S. Dispensatory, a reference work Porter used when he was in the prison pharmacy. Further confusing the issue is that for at least one short story, and for a later autobiographical author profile, Porter signed the "full" name Olivier Henry.
Porter also used a number of other noms de plume, most notably "Alex, Longford", and continued using a variety of pen names full-time when he took a writing contract for Ainslee's Magazine in New York City shortly after his release from prison. Eventually, "O. Henry" became the name that was most recognized by magazine editors and the reading public, and therefore led to the greatest fees for story sales. Accordingly, after about 1903 Porter used the "O. Henry" byline exclusively.
In fact, after his prison term Porter almost never identified himself in print by his real name, even in private correspondence to close friends. To editors, he was simply O. Henry (or occasionally Olivier Henry). When writing to friends, however, he would routinely sign his letters with one of a wide range of deliberately nonsensical pseudonyms, such as "Horatio Swampwater".
A Brief Stay At The Top
Porter married again in 1907 to his childhood sweetheart, Sarah Lindsey Coleman. However, despite the success of his short stories being published in magazines and collections (or perhaps because of the attendant pressure success brought), Porter became an alcoholic. Sarah left him in 1909, and he died in 1910 of cirrhosis of the liver. After funeral services in New York City, he was buried in Asheville, North Carolina. His daughter, Margaret Worth Porter, died in 1927 and was buried with her father.
Attempts were made to secure a presidential pardon for Porter during the administrations of Woodrow Wilson, Dwight Eisenhower and Ronald Reagan. However, each attempt was met with the assertion that the Justice Department did not recommend pardons after death. This policy was clearly altered during the administration of Bill Clinton (who pardoned Henry Flipper), so the question of a pardon for O. Henry may yet again see the light of day.
O. Henry stories are famous for their surprise endings. He was called the American Guy De Maupassant. Both authors wrote twist endings, but O. Henry stories were much more playful and optimistic.
Most of O.Henry's stories are set in his own time, the early years of the 20th century. Many take place in New York City, and deal for the most part with ordinary people: clerks, policemen, waitresses. His stories are also well known for witty narration.
The Four Million (a collection of stories) opens with a reference to Ward McAllister's "assertion that there were only 'Four Hundred' people in New York City who were really worth noticing. But a wiser man has arisen—the census taker—and his larger estimate of human interest has been preferred in marking out the field of these little stories of the 'Four Million'". To O. Henry, everyone in New York counted. He had an obvious affection for the city, which he called Baghdad on the Subway, and many of his stories are set there—but others are set in small towns and in other cities.
His famous story A Municipal Report opens by quoting Frank Norris: "Fancy a novel about Chicago or Buffalo, let us say, or Nashville, Tennessee! There are just three big cities in the United States that are 'story cities' — New York, of course, New Orleans, and, best of the lot, San Francisco." Thumbing his nose at Norris, O. Henry sets the story in Nashville.
Fundamentally a product of his time, O. Henry's work provides one of the best English examples of catching the entire flavor of an age. Whether roaming the cattle-lands of Texas, exploring the art of the "gentle grifter", or investigating the tensions of class and wealth in turn of the century New York, O. Henry had an inimitable hand for isolating some element of society and describing it with an incredible economy and grace of language. Some of his best and least-known work resides in the collection "Cabbages and Kings", a series of stories which each explore some individual aspect of life in a paralytically sleepy South American town while each advancing some aspect of the larger plot and relating back one to another in a complex structure which slowly explicates its own background even as it painstakingly erects a town which is one of the most detailed literary creations of the period.
Spoiler warning: Plot and/or ending details follow. O. Henry is so famous for his unexpected plot twists that this warning is especially important.
A famous story of his, "The Gift of the Magi", concerns a young couple who are short of money but desperately want to buy each other Christmas gifts. Unbeknownst to Jim, Della sells her most valuable possession, her beautiful hair, in order to buy a platinum fob chain for Jim's watch; unbeknownst to Della, Jim sells his most valuable possession, his watch, to buy jeweled combs for Della's hair. The essential premise of this story has been copied, re-worked, parodied, and otherwise re-told countless times in the century since it was written.
The Ransom of Red Chief concerns two men who kidnap a boy of ten. The boy turns out to be so bratty and obnoxious that the desperate men ultimately pay the boy's father two hundred and fifty dollars to take him back.
The Cop and the Anthem concerns a New York City hobo named Soapy, who sets out to get arrested so he can spend the cold winter as a guest of the city jail. Despite efforts at petty theft, vandalism, disorderly conduct, and "mashing", Soapy fails to draw the attention of the police. Disconsolate, he pauses in front of a church, where an organ anthem inspires him to clean up his life - whereupon he is promptly arrested for loitering.
In A Retrieved Reformation, safecracker Jimmy Valntine gets a job in a small town bank to case it for a robbery. Unexpectedly, he falls in love with the banker's daughter, and decides to go straight. Just as he's about to leave to deliver his specialized tools to an old associate, a lawman who recognizes him arrives at the bank, and a child locks herself in the airtight vault. Knowing it will seal his fate, Valentine cracks open the safe to rescue the child - and the lawman lets him go.
 Cultural relations
O. Henry once said: "There are stories in everything. I've got some of my best yarns from park benches, lampposts, and newspaper stands." 
The O. Henry Awards are yearly prizes given to outstanding short stories.
The O. Henry Pun-Off World Championships are held in May of each year in Austin, Texas, hosted by the city's O. Henry Museum.
O. Henry is a household name in Russia, as his books enjoyed excellent translations and some of his stories were made into popular movies, the best known being, probably, "The Ransom of Red Chief". The phrase "Bolivar cannot carry double" from "The Roads We Take" has become a Russian proverbs, whose origin many Russians do not even recognize.
O. Henry's first wife, Athol, was probably the model for Della.
In 1952 a film featuring five O. Henry stories was made. The primary one from the critic's acclaim was "The Cop and the Anthem" starring Charles Laughton and Marilyn Monroe. The other stories are "The Clarion Call," "The Last Leaf," "The Ransom of Red Chief," and "The Gift of the Magi."
There is an O. Henry Middle School in Austin.