The following is a list of real or historical people who have been portrayed as President of the United States in fiction, although they did not hold the office in real life. This is done either as an alternate history scenario, or occasionally for humorous purposes. Also included are actual US Presidents with a fictional presidency at a different time and/or under different circumstances than the one in actual history.

S Barry Sadler Barry Sadler is elected president in 1984 in Mitchell J. Freedman's novel A Disturbance of Fate. A Republican, Sadler's pursuit of conservative policies triggers a second civil war that, after much destruction, results in his arrest and the drafting of a new Constitution in which the office of the presidency is abolished.

Arnold Schwarzenegger He is mentioned as a prior commander in chief in Demolition Man with his own presidential library in San Angeles, California. "President Schwarzenegger" was also mentioned in the Doctor Who episode "Bad Wolf". In the 2007 film The Simpsons Movie, Arnold Schwarzenegger is shown as the president. In the movie, he is a near replica of Rainier Wolfcastle, who is himself a parody of Schwarzenegger. He gives uninformed orders to EPA Administrator Russ Cargill to seal Springfield under a giant glass dome after Lake Springfield becomes horrifically polluted because of Homer Simpson dumping pig feces in it. When Cargill warns of the possibility of a public backlash after learning of Springfield becoming a no man's land (and subsequently manipulates the President into authorizing the destruction of Springfield), Schwarzenegger laments returning to making family comedies, such as "Diaper Genie" in reference to the real Schwarzenegger's failed attempts to leave the action genre. According to The Simpsons creator Matt Groening, Schwarzenegger was the president in the film rather than then-President George W. Bush because, according to Groening, "in two years ... the film [would be] out of date". He was voiced by Harry Shearer in the film.

William Scranton In the 1980 novel Timescape by Gregory Benford, the assassination of John F. Kennedy on November 22, 1963, was averted by a high school student who interrupted Lee Harvey Oswald at the Texas School Book Depository, attacking the shooter and sending the would-be fatal third shot awry. Although seriously injured, Kennedy survived. This interference created an alternate timeline in which William Scranton was the US president in 1974, having defeated Robert F. Kennedy due to a telephone tapping scandal.

William H. Seward In the short story "The Lincoln Train" by Maureen F. McHugh contained in the anthology Alternate Tyrants edited by Mike Resnick, Secretary of State William Seward became the 17th President in 1865. His predecessor Abraham Lincoln was the victim of an assassination attempt in Ford's Theatre on April 14, 1865. He survived but John Wilkes Booth's bullet remained lodged in his brain and he was rendered a vegetable. President Seward organised population transfers of Southern civilians who had owned slaves to the Western territories on a neo-Trail of Tears, where they are left to die of starvation and disease.

Horatio Seymour Note: In actual history, Seymour was a major Democratic Party politician during and after the American Civil War, and a Presidential candidate in 1868. It is reasonable to assume that, had the South won the Civil War – which would have severely discredited the Republican Party – Seymour might have been elected President of the Rump US. However, his fictional presidencies widely diverge from each other. In Ward Moore's "Bring the Jubilee", during Horatio Seymour's term the United States suffered the severe economic results of its defeat in the War of Southron Independence and the reparations it had to pay to the victorious Confederacy. Inflation, which already entered galloping state under Seymour's predecessor Clement Vallandigham, became dizzying under President Seymour and precipitated the food riots of 1873 and 1874. The economy was later stabilized, but the rump United States was permanently crippled and went into the 20th Century as a poor backwards country. (Note: The book does not make clear if Seymour had two terms, 1868 and 1872, after a single one by Vallandigham, or only a single one in 1872 after two of Vallandigham.) In the alternate history novel The Guns of the South by Harry Turtledove, Horatio Seymour secured the Democratic presidential nomination in the immediate aftermath of the Second American Revolution (1861–1864), running on a ticket with Clement Vallandigham as his running mate. He narrowly defeated President Abraham Lincoln in the 1864 election. The election was a close one and it was over a week before Seymour's victory was determined. During the election, he won 41.5% of the popular votes with 1,671,580 voted and carried 10 states (New York, Pennsylvania, Ohio, Indiana, Kentucky, Missouri, Wisconsin, Maryland, Oregon, and California) and received 138 electoral votes. He was inaugurated as the 17th President on March 4, 1865. Under President Seymour, the United States shifted its focus from its southern border to its northern one. In 1866, the British Empire increased the size of its garrison in the Dominion of Canada, prompting the President to pull troops out of the New Mexico Territory and the Arizona Territory. The United States, still heavily militarized from fighting the Second American Revolution, was able to successfully invade and hold Canada in short order, leading to a war with the United Kingdom. General George B. McClellan had been one of the most prominent advocates of the annexation of Canada. In The Confederate States of America: What Might Have Been by Roger L. Ransom, Horatio Seymour won the presidential election of 1864 and became the 17th President. He recognized the Confederacy as an independent nation after the South's victory in the American Civil War.

James S. Sherman In S.M. Stirling's series Tales From the Black Chamber, William Howard Taft died shortly before the 1912 Republican National Convention. Although Taft's Vice President James S. Sherman succeeded him to become the 28th President, Theodore Roosevelt went on to win the Republican nomination and a third term in the presidential election. Roosevelt and his inner circle speculated that Sherman's poor health would preclude him from succeeding Taft as the Republican nominee. As Sherman died on October 30, 1912 in real-life, it is not mentioned whether he lived longer and served the remainder of Taft's term or died in office before its end.

William Tecumseh Sherman In the alternate history novel By Force of Arms by Billy Bennett, William Tecumseh Sherman became president. In this timeline, Stonewall Jackson survived the Battle of Chancellorsville and the Confederate States of America won the Battle of Gettysburg and the American Civil War, but six years later Sherman was elected president and the war broke out again.

O. J. Simpson In the final episode of the original run of the satirical UK TV series Spitting Image, O. J. Simpson is depicted as a future U.S. president who is tricked into starting a nuclear war by Noel Edmonds and Mr. Blobby, as part of a series of sketches called 'The Last Prophecies of Spitting Image'.

Upton Sinclair