It can be variously seen as a sub-genre of literary fiction, science fiction, and historical fiction ; different alternate history works may use tropes from any or all of these genres.

Since the 1950s, this type of fiction has to a large extent merged with science fictional tropes involving cross-time travel between alternate histories or psychic awareness of the existence of " our " universe by the people in another ; or ordinary voyaging uptime ( into the past ) or downtime ( into the future ) that results in history splitting into two or more time-lines.

Cross-time, time-splitting and alternate history themes have become so closely interwoven that it is impossible to discuss them fully apart from one another.

In French, Italian, Spanish and German, alternate history novels are called uchronie.

" This term apparently also inspired the name of the alternate history book list, uchronia. net.

In writing an alternate history, the author makes the conscious choice to change something in our past.

According to Steven H Silver, alternate history requires three things: 1 ) the story must have a point of divergence from the history of our world prior to the time at which the author is writing, 2 ) a change that would alter history as it is known, and 3 ) an examination of the ramifications of that change.

Science fiction set in what was the future but is now the past, like Arthur C. Clarke's 2001: A Space Odyssey or Nineteen Eighty-Four, are not alternate history because the author has not made the conscious choice to change the past.

Secret history, works that document things that are not known to have happened historically but would not have changed history had they happened, is also not to be confused with alternate history.

* List of alternate history fiction

Focuses on Watchmen as alternate history.

* AlternateHistory. com-largest alternate history discussion forum on the Internet.

* Althistory Wikia-an alternate history wiki, maintained by Wikia.

* Counter-Factual. net-site dedicated to alternate history as well as other topics, such as science fiction and creative writing.

* HistoryAlternate. com-another alternate history discussion forum.

* Soc. history. what-if-the usenet newsgroup on alternate history with over a decade of archives.

* Alternate History Weekly Update: a blog featuring commentary on alternate history news.

* Paradox: The Magazine of Historical and Speculative Fiction, frequently publishes alternate history stories.

* Uchronia has an introduction to the topic, and lists over 2000 works of alternate history.

* Moriarty by Modem, a short story by Jack Nimersheim, describes an alternate history where Babbage's Analytical Engine was indeed completed and had been deemed highly classified by the British government.

Additionally, in the alternate history novel Ruled Britannia by Harry Turtledove, Boudicca is the subject of a play written by William Shakespeare to incite the people of Britain to revolt against Spanish conquerors.

* The character of Ada and her home Ardis Hall in the Ilium cycle are inspired by Vladimir Nabokov's novel Ada or Ardor, which was Nabokov's foray into the science fiction genre and alternate history.

* Frederick Douglass is a major character in the alternate history novel How Few Remain by Harry Turtledove.

The story was slightly altered and the title changed to King Kong vs. Prometheus, returning the name to the original Frankenstein concept ( The Modern Prometheus was the alternate name of Frankenstein in the original novel ).

The 2005 Kazuo Ishiguro novel Never Let Me Go and the 2010 film adaption are set in an alternate history in which cloned humans are created for the sole purpose of providing organ donations to naturally born humans.

Ribbentrop is also a key figure in the historical novel Famous Last Words by Timothy Findley ( Penguin Books 1982, ISBN 0-14-006268-8 ) and Harry Turtledove's alternate history series Worldwar where his Soviet counterpart Molotov frequently expresses contempt for his lack of intelligence.

* The 2003 novel Fox at the Front by Douglas Niles and Michael Dobson depicts Philby selling secrets to the Soviet Union during the alternate Battle of the Bulge where German Field Marshal Erwin Rommel turns on the Nazis and assists the Allies in capturing all of Berlin.

The whimsical Svetz series consists of a collection of short stories, The Flight of the Horse, and a novel, Rainbow Mars, which involve a nominal time machine sent back to retrieve long-extinct animals, but which travels, in fact, into alternate realities and brings back mythical creatures such as a Roc and a Unicorn.

* Transformation, an alternate title for The Marble Faun, a novel by Nathaniel Hawthorne

After expanding on Neuromancer with two more novels to complete the dystopic Sprawl trilogy, Gibson became an important author of another science fiction sub-genre — steampunk — with the 1990 alternate history novel The Difference Engine, written with Bruce Sterling.

In addition, Ten Little Niggers ( 1939 ) was the original British title of Agatha Christie's novel And Then There Were None, which has also been known by the alternate title Ten Little Indians.

* Lest Darkness Fall ( 1939 )-an early alternate history novel that helped define the genre

* Bryan Talbot's graphic novel Grandville is set in an alternate history in which France won the Napoleonic War, invaded Britain and guillotined the British Royal Family.

Emperor Go-Daigo appears in the alternate history novel Romanitas by Sophia McDougall.

Longstreet is a character in Harry Turtledove's alternate history novel, How Few Remain, and in Robert Conroy's alternate history novel, 1901.

* In Harry Turtledove's alternate history novel The Guns of the South, Pleasants proposes and enacts his plan for a similar battle when the South engages in war with their time-traveling benefactors.

* Rogers was the heroine of a novel, Ginger Rogers and the Riddle of the Scarlet Cloak ( 1942, by Lela E. Rogers ), in which " the heroine has the same name and appearance as the famous actress but has no connection ... it is as though the famous actress has stepped into an alternate reality in which she is an ordinary person.

One of the most successful titles, Frank Tousey ’ s New York Detective Library eventually came to alternate stories of the James Gang with stories of Old King Brady, detective, and in a rare occurrence in the dime novel world, there were several stories which featured them both, with Old King Brady doggedly on the trail of the vicious gang.

* In the alternate history novel Ruled Britannia, predicated on the victory of the Spanish Armada in 1588, he and his father organise the English resistance movement against the Spanish with the help of William Shakespeare.

The line is further blurred by novelists such as Kim Stanley Robinson, whose alternate-history novel The Years of Rice and Salt has a character talking of historians ' use of counterfactuals, within the novel's alternate history.

Nicephorus III is also a fictional Byzantine Emperor ruling in the beginning of the 14th century in Harry Turtledove's alternate history novel Agent of Byzantium.

* In the Doctor Who spin-off novel State of Change, the Sixth Doctor and Peri Brown meet and befriend an alternate version of Ptolmey in a timeline where Cleopatra and Anthony survived thanks to them acquiring a copy of the Doctor's TARDIS console, using the information in its databanks to develop modern technology and weapons centuries ahead of schedule.