Harry Harrison (1925-2012; born Henry Maxwell Dempsey) was a science fiction writer.

He is best known for his humorous SF, which includes ''Literature/TheStainlessSteelRat'' series, the ''Literature/BillTheGalacticHero'' series, and the stand-alone novels ''Literature/TheTechnicolorTimeMachine'' and ''Literature/StarSmashersOfTheGalaxyRangers''.

He has also written serious SF, including ''Literature/MakeRoomMakeRoom'', which inspired the film ''Film/SoylentGreen'' (although the film's most famous plot element was not in the book); the ''Literature/{{Deathworld}}'' trilogy; the ''Literature/ToTheStars'' trilogy; and the ''Literature/WestOfEden'' trilogy.

!!Works by Harry Harrison with their own trope pages include:
* ''Literature/BillTheGalacticHero'' series
* ''Literature/{{Deathworld}}'' series
* ''Literature/TheHammerAndTheCross'' trilogy
* ''Literature/InvasionEarth''
* ''Literature/MakeRoomMakeRoom''
* ''Literature/TheStainlessSteelRat'' series
* ''Literature/StarSmashersOfTheGalaxyRangers''
* ''Literature/TheTechnicolorTimeMachine''
* ''Literature/ToTheStars'' trilogy
* ''Literature/TheTuringOption'' (with Marvin Minksy)
* ''Literature/WestOfEden'' trilogy

!!Other works by Harry Harrison provide examples of:

* AlternateHistory
** In ''A Transatlantic Tunnel, Hurrah!'', America [[AmericaIsStillAColony lost the War of Independence]] and remained part of the British Empire. (Also, an earlier military defeat changed Spanish history enough that Christopher Columbus couldn't get funding, leaving American to be discovered by John Cabot in 1497.)
** The ''Stars & Stripes'' series envisions the Trent incident from the American civil war blowing up into a full-scale war between the United States and the British Empire. A navigational error brings the Confederacy in on the Union side, ending the civil war, and resulting in the British getting their asses handed to them by Generals Lee, Grant, Sherman, and Stonewall Jackson.
* AlternateTechline: ''Tunnel Through the Deeps'' (AKA ''A Transatlantic Tunnel, Hurrah!'') takes place in a world where UsefulNotes/TheAmericanRevolution failed with all the "rebels" executed. In the late 20th century, there is an alternate UsefulNotes/ColdWar between the two superpowers: Great Britain and France. There are gigantic airplanes, powered by nuclear reactors, the technology to build a maglev tunnel at the bottom of the Atlantic, and ballistic missiles, but mechanical calculators are still the norm with "computers" being seen as something newfangled and unreliable.
* AmericaIsStillAColony: In ''Tunnel Through the Deeps'', due to the fact it was John Cabot, not UsefulNotes/ChristopherColumbus, who discovered North America, Spain was also never unified and unable to fund Columbus. This lead to a scenario where the revolutionary war was lost and UsefulNotes/GeorgeWashington was shot as a traitor. The main character is a descendant of Washington who feels tarred by his family's bad reputation whilst working on a transatlantic tunnel between the British Isles and the Northern American colonies.
* ArtificialGravity: The discovery of a way to reduce gravity drives the plot of ''The Daleth Effect'' (aka ''In Our Hands, the Stars''). The discoverer specifically mentions that the knowledge could be used to do horrible things, such as grabbing chunks of the Moon and dropping them on an enemy country. The use of the device, for example, allows a craft (which doesn't even need proper engines) to travel to the Moon within hours and to Mars within days.
* BlueAndOrangeMorality: The aliens in ''The Jupiter Plague'' (AKA ''Plague from Space'') behave in ways that humans often find horrifying and inexplicable, due to the different outlook being a HiveMind gives them.
* CarCushion: Played with in "Portrait of the Artist", in which [[spoiler:a comic book artist, who has just lost his job to a machine, creates a suicide note in comic-book form that ends with a depiction of him jumping off his publisher's office building and landing on a car. After he commits suicide in the manner depicted, his ex-boss's only reaction is remark that he landed on the wrong car]].
* CargoCult: In "The Repairman", a man is sent to repair an ancient, RagnarokProof hyperspace beacon on a distant planet. It turns out the builders failed to notice a few stone age reptiles. Since then, the natives found the beacon (a huge tower), and made it a holy shrine (it produced an endless spring of water as part of its coolant system). One of the priests, while cleaning inside, hit the emergency shutdown switch. The protagonist pretends to be a sentry of heaven, sent to restore the spring.
* ChildSoldiers: In "War With the Robots", the command staff are all teenagers as anyone older lacks the reflexes and flexibility of mind needed to fight the war. They retire after four or five years.
* ConspicuouslyPublicAssassination: In the ''Stars and Stripes'' AlternateHistory trilogy, John Wilkes Booth tries to assassinate UsefulNotes/AbrahamLincoln in public by firing out the crowd, after missing his chance at Ford's Theater (in this timeline, Lincoln didn't make it to the play due to the illness of his son).
* CranialProcessingUnit: In a short story, an android cop averts this trope because he has a recoilless cannon in his head, up near the eyes for good aiming.
* CurbStompBattle: In the AlternateHistory ''Stars and Stripes'' trilogy, the long war between Britain and the United States is presented as one long CurbStompBattle due to the United States' overwhelming technological and tactical superiority -- by the third book, the Americans are almost 100 years ahead of the British, having UsefulNotes/WorldWarI-era battleships and tanks in 1870. In the course of the series, there are only three notable times where the British actually have the upper hand: the British army capturing a Southern town (somewhat accidentally, [[EpicFail as they were intending to capture a Northern outpost]]), a Highlander regiment capturing a fort near New York, and a British ironclad sinking an American one. Every other battle in the series, all resounding American victories.
* DeadAllAlong: The short story "The Pliable Animal" deals with the murder of a prince visiting another planet. The prince rode a car from the planet's royal palace home when he suddenly shouted at the driver to stop, ran into a dark alley, and was found dead there. It turns out toward the end that [[spoiler:a secret underground passage lead to that alley from the palace. An imposter entered the car, shouted for the driver to stop, and ran for the agreed upon spot where they placed the prince's corpse]].
* EarthThatUsedToBeBetter: In the Brion Brandd duology, it's established that Earth is overpopulated and polluted. At the same time, it's still an important planet.
* EnemyMine: This is the plot of the ''Stars and Stripes'' AlternateHistory trilogy. After the British declare war on the Union, they accidentally sack a Confederate town instead of a Union fort (the stars-and-bars flag confuses them). In response, the Union and the Confederacy agree to a cease-fire and combine forces against the British.
* EveryoneKnowsMorse: Deconstructed in ''Spaceship Medic'', set on a heavily damaged spaceship some time in the future. The radio has been jury-rigged back into operation, and the only signals it can send that are powerful enough to reach help are bursts of static. They have to revive the now ancient and obsolete Morse code in order to send messages via bursts of static. Meanwhile, the recipients on Mars are left scrabbling through the history books to find out how to translate the strange signals.
* FamilyHonor: ''Tunnel Through the Deeps'' (aka ''A Transatlantic Tunnel, Hurrah'') has British engineer Captain Augustine Washington working to complete said tunnel to restore his family's honor lost when his ancestor George Washington was shot as a traitor to King George III.
* FasterThanLightTravel: In "The Repairman", hyperspace is featureless by itself, so a ship entering cannot determine where it is, where it moves, or even whether it does at all. As such, humanity builds special beacons all over the galaxy, allowing for position triangulation by their individual codes.
* FirstContact: In ''Plague from Space'', a ship sent to explore Jupiter discovers that the solid core of Jupiter is inhabited by a HiveMind race whose hat is OrganicTechnology. This has unpleasant consequences for the explorers, and then for Earth, before the two planets are able to reach an understanding.
* GenerationShips: In ''Captive Universe'', a generation ship with a seamless environment is launched; by design the highly repressive, extremely stable Aztec cities onboard believe themselves to be in an inaccessible river valley. The ship tenders are if anything more rigid and religious: an extraordinary asceticism rules their lives and repairs are sacred rituals.
* GunshipRescue: In ''Stars and Stripes Forever'', Washington D.C. is being invaded until the ironclad ''Avenger'' arrives to save the day.
* HideousHangoverCure: The Drive-Right pill, which appears in more than one series, is a small round pill that will make you absolutely stone cold sober seconds after swallowing it... it's completely black except for a skull and crossbones on each side. Unfortunately it's rather unpleasant to take.
* HumansThroughAlienEyes: In "The Streets of Ashkelon", a human missionary converts an alien culture to UsefulNotes/{{Christianity}}. [[spoiler:The aliens then try to initiate the millennium of the missionary's message by crucifying him and waiting for him to rise on the third day.]]
* HumanSubspecies: The short story "Final Encounter" had a team with members of two Human Subspecies looking for nonhuman intelligence. [[spoiler:At the end, the very promising new species, which can't even breathe the same air we do, turns out to be of Earth descent too -- one group was expanding and searching clockwise around the galaxy, the other counter-clockwise]].
* IfItSwimsItFlies: In ''The Daleth Effect'' (aka ''In Our Hands, the Stars''), the main characters use the titular effect to modify a mini-sub into a spaceship.
* IMadeCopies: "The Repairman", a comic sci-fi short story, has DaChief bullying one of his men to take on a mission instead of going on leave, citing a clause in his contract, which he produces for effect. The hero draws his raygun and disintegrates it, but the computer just prints out another one. Then the Chief docks his pay for the cost of printing the copy.
* ImprobableAge: Justified in "War With the Robots"; the command staff are all teenagers as anyone older lacks the reflexes and flexibility of mind needed to plot strategy in the fast-paced war. They retire after four or five years.
* InertialDampening: ''Tunnel Through The Deeps'' (AKA ''A Transatlantic Tunnel, Hurrah!'') has a sequence featuring a new method of rapid intercontinental travel. They submerge the protagonist (with a breathing apparatus) into a fluid-filled rocket that is launched in a ballistic trajectory, allowing him to safely get from North America to Britain in a few hours. The best part is that all calculations were done using a mechanical computer.
* InTheFutureHumansWillBeOneRace: An attempt to invoke this occurs in "A Brave Newer World", where natural childbirth is on the downtrend and bottled babies are at the first stages of becoming the norm. The government program apparently figures that since they'll be growing the next generations, they can see about removing troublesome genes while they're at it. Unfortunately, their definitions of 'troublesome' includes many involving skin tone and eye shape. The doctor in charge of the project goes to great lengths to expose this bias towards Nordic and Anglo-Saxon ancestry.
* JobStealingRobot: "Portrait of the Artist" is about a comic strip artist who loses his job to a machine.
* KarmaHoudini: In the ''Stars and Stripes'' AlternateHistory trilogy, an American ship captain blows up a British ship without provocation. Why? Because he wants a fight. It's not even much of a fight, as the American ship blows the opponent away with two volleys from its main guns, and the Brits don't even have time to react. That incident is quickly forgotten, and the captain in question gets away scot-free.
* MechanicalEvolution: The short story "The War with the Robots". With war becoming ever-deadlier, humans retreat to bunkers deep underground, using robots to fight. The robots on either side design ever more effective robot forms, eventually able to drive the humans out of the opposing bunkers. The now-obsolete human race is shocked to find itself sidelined from what used to be their war.
* MilitaryMashupMachine: Spoofed in the short story "Navy Day". The US Army declares their waterborne rivals obsolete after developing a technology that enables vehicles to drive on the ocean. Naval scientists work frantically while Congress debates whether to abolish the Navy once and for all; just as they are about to vote in favor the Admiral points to the battleship now 'sailing' down Constitution Avenue.
* MobileSuitHuman: The inverse (a human concealed inside a robotic alien suit) happens in "The Repairman".
* RobotWar: In "War With the Robots", the human occupants of a command headquarters are forced out of their underground base by robot attack, leaving it to be manned by their own robots. On reaching the surface they find the enemy command staff living as farmers on the war-torn battlefield above -- it turns out the robots on both sides find they can conduct the war more efficiently once humans are out of the way. The protagonist is deeply miffed.
* SenselessSacrifice: In ''The Daleth Effect'', Denmark's space liner is invaded by US and USSR agents in an attempt to steal the piece of AppliedPhlebotinum allowing the ship to fly. In response, the captain of the ship triumphantly tell both parties that all their efforts are in vain, as a fail-safe has been installed on board to prevent a takeover. The ship is destroyed seconds later. The captain's widow laments that all the crewmembers and passengers, including the inventor of the device, died in vain to protect a secret that was already made public days before. Even worse, since Denmark refused to patent the technology for fear of it being misused, they now have nothing.
* SteamNeverDies:
** In ''Planet Story'', an admiral who just happens to be a railfan specifically orders a spaceport built on the opposite side of the continent from the mine just to have an excuse to play with trains. His personal toy is a gold plated full scale replica of a Union Pacific Big Boy, the largest steam engine ever built. It's actually nuclear powered (Harrison describes it as powerful enough "to pull a battleship sideways across a mudflat") but it does produce enough steam to blow the whistle.
** In the alternate timeline of ''A Trans Atlantic Tunnel, Hurrah!'', Great Britain is the only country to have discovered atomic power. Naturally, they use it solely to power one steam locomotive.
* WhatIsThisThingYouCallLove: Satirized in "The Robot Who Wanted To Know". Sophisticated robot librarians designed to think independently often focus on a particular area of interest; Filer 13B-445K's interest is human concepts of love and romance. After reading up on it he wants to experience it personally and goes to some lengths to disguise himself as an attractive man for a costume ball. Naturally the busty heroine ends up falling for him and is outraged to discover his mechanical identity. He responds by [[LogicBomb nosediving into a paradox spiral and self-destructing]]. Workers examining the wreck later find a malfunction in the central pump and joke that "you could almost say he died of a broken heart".
* YouAreInCommandNow: In ''Spaceship Medic'', the eponymous medic ends up in charge after all the rest of the ship's officers are wiped out by a meteorite hitting the bridge (then has some adventures, saves the day, and goes back to being a doctor).