John Keith Laumer (June 9, 1925 January 23, 1993) was an American science fiction writer. He is particularly known for the UsefulNotes/NebulaAward-nominated novel ''A Plague of Demons'', and for two series:

* Literature/{{Bolo}}. The bolos are automated battle-tanks, originally developed to reduce the number of human crew required; later models are able to perform programmed tasks without any crew at all, and still later models are self-aware artificial intelligences in armor-plated bodies equipped with enough firepower to conquer an entire planet single-handed. The series is a set of mostly self-contained stories sampling events across the history of bolo development; in the later stages, the sometimes-tense relationship between the bolos and the humans they serve is inevitably a feature. This has become a SharedUniverse, with authors like Creator/DavidWeber and Creator/JohnRingo being the most recent contributors.
* Literature/{{Retief}}. Satirical series of stories about the travails of Jame Retief, a junior member of Earth's interstellar diplomatic corps. Inspired by Laumer's career in the United States Foreign Service.

His humorous AlienInvasion thriller, ''The Monitors'', was made into a fairly faithful low-budget movie in 1969, and his humorous HardboiledDetective story ''Deadfall'' was made into the 1976 movie ''Peeper'' starring Creator/MichaelCaine and Creator/NatalieWood.
!!Works by Keith Laumer with their own trope pages include:
* ''Literature/{{Bolo}}'' series
* ''Literature/LafayetteOLeary'' series
* ''Literature/{{Retief}}'' series
* ''[[Literature/DangerousVisions "Test to Destruction"]]''
!!Other works by Keith Laumer provide examples of:

* AllohistoricalAllusion: In one of the ''Imperium'' novels, a mild-mannered fellow named Hermann Göring is delighted to learn that in the hero's home timeline he is instantly recognizable and has the dashing title of Reichsmarschall. The hero mercifully doesn't explain the context.
* AlternateHistory: The ''Worlds of the Imperium'' series includes one where WWI and the Russian Revolution never happened, one where Neanderthals ruled, one where Napoleon beat the British, and one where rats became the dominant sentient species.
* AlternateTimeline: ''Worlds of the Imperium'' more or less deconstructs this. Decision points spawn alternate universes, but the vast majority of them are barren and devoid of life because the direction of technological experimentation which can eventually lead to an interdimensional travel machine turns out to be ''millions'' of time more likely to to lead accidentally to an apocalyptic weapon. Hence, only a bare few timelines with advanced technology actually survive.
* BackupBluff: ''The Glory Game'':
** Most of the Terran space fleet has left Earth to check out a collection of Hukk ships in another area of space. Commodore Dalton figures out that the ships are a lure and the Hukk are planning a sneak attack to capture the Lunar fortifications. When the Hukk fleet appears near Earth, he bluffs its commander into surrendering by telling them that the rest of the Terran fleet is only minutes away.
** Later on, when a single Hull ship lands on a frontier planet Dalton sets up energy rifles on hills surrounding the ship, After disabling the ship, he tricks the crew into surrendering by making them think they're surrounded by troops. Another character calls Dalton's ploy "the Fort Zinderneuf ploy".
* BenevolentAlienInvasion: ''The Monitors'' has benevolent aliens ruling the Earth, "opposed" by various misfit rebels.
* BrainInAJar: In ''A Plague of Demons'', human brains are installed in alien war machines.
* CuckooNest: ''Knight of Delusions'' (also published, confusingly, as ''Night of Delusions'') puts its hero through an insane number of alternate realities. Every time it becomes entirely unbelievable, he gets put into yet another one and is back at square one, trying to figure out if he's completely out or if he's stuck in yet another false reality.
* DoorstopBaby: ''[[ Doorstep]]'' featured a huge insect- or crustacean-looking thing that took the army with lots of artillery to kill it -- and then they decoded the message which read, "Please take good care of my little girl."
* DoubleReverseQuadrupleAgent: One of these is the main character of ''Dinosaur Beach'', leading to multiple levels of TomatoSurprise as he betrays one faction or another. His ultimate allegiance turns out to be to [[spoiler:''none'' of the main factions, as none of them are willing to acknowledge their own contribution to the problem they're all trying to fix]].
* EasilyThwartedAlienInvasion: A short story in which aliens invade a dying civilization -- only to discover that the locals were in fact immortals whose metabolisms shut down if they didn't get enough of a certain gas in their air. Guess what the invaders exhaled. And the locals who were still up and about were the ''weakest'' of their species; the invasion revived all of their brawny badasses.
* EmergencyImpersonation: In ''Worlds of the Imperium'', the protagonist is dragooned by agents from the Imperium's AlternateHistory to replace a dictator (the version of himself from a third Alternate History).
* ExpendableAlternateUniverse:
** In the ''Imperium'' stories, the "Maxoni-Cocini drive" allows access to parallel timelines -- but at the risk of destroying one's home time-line in an unspecified chrono-nuclear disaster. In fact, our Earth is in the middle of a Blight made up of timelines where the M-C drive went horribly wrong.
** ''Dinosaur Beach'' explores parallel time and the Timesweepers who have to clean up the messes left by previous time-travelers while fighting off others who don't want the extant lines cleaned up.
* EveryoneKnowsMorse: Subverted in ''Worlds of the Imperium''. Bayard reaches the broken MK drive (essentially a teleporter between parallel worlds) and jury-rigs it to transmit SOS, hoping that Imperium diverged from "our" Earth after Morse code was created and they should understand the signal and save him. They don't understand the signal, but the existence of an odd powerful signal from where Bayard was sent to prompts them to send a team to investigate.
* GenocideDilemma: In ''The Glory Game'', after the warlike alien Hukk are defeated, the Terran Hardliners want to wipe them out to keep them from threatening Earth again.
* ImpersonatingTheEvilTwin: In ''Imperium'', a man is recruited by an interdimensional empire that occupies alternate Earths. His mission is to replace the overlord of one of these realities, who is his alternate self.
* InstantExpert: In ''Galactic Odyssey'', the protagonist is put to work sorting indistinguishable glorm-bulbs... which turns out to give him the ability to learn essentially anything with a single run-through.
* MemoryJar: In ''A Trace of Memory'', an amnesiac alien living as a human on Earth must recover the device in which his full memories are stored. He later discovers that on his home planet almost everyone has this problem.
* MysteriousAntarctica: In ''The Breaking Earth'', an ancient pre-ice-age civilization is discovered to have left its city and advanced technology behind in Antarctica.
* OmnicidalNeutral: ''Dinosaur Beach'' demonstrates an extreme, but [[IDidWhatIHadToDo ultimately heroic]], version of this trope. The setting has been deeply screwed up by the invention of time travel, with each faction trying to prevent any time travel in its "future," but at the same time trying to prevent the prevention of time travel in its "past," since all of them are the futures of factions that were unable to prevent time travel, and none of them wish to be [[RetGone erased from the timestream]]. Meanwhile, each time trip is making the fabric of reality less and less stable. [[spoiler:The main character's solution is to travel back and prevent the invention of time travel, preventing the collapse of the universe at the cost of the lives and existences of every member of every faction in the book. He's one of only two characters, named or unnamed, who comes from a future timeline but still exists at the story's close.]]
* PantsFree: In ''Worlds of the Imperium'', this is a plot point. The hero is sent to impersonate his alternate universe counterpart, the ruler of an evil empire. The people sending him copy the ruler's uniform from his TV broadcasts, but have to guess on the pants, since the ruler is only seen from the waist up. [[spoiler:When the hero gets there, he discovers why: the ruler lost his legs in battle during his rise to power, but had been keeping it secret from the public. So much for impersonation.]]
* RealityWarper: ''Knight of Delusions'' at one point pits two reality warpers against each other, which ends up reading a lot like a pair of little kids playing pretend at each other and shouting things like "NUH-UH, I'VE GOT NUKE PROOF ARMOR" to ward off attacks.
* RepetitiveName: Chester W. Chester IV in ''The Great Time Machine Hoax''.
* RightOnQueue: "In the Queue", nominated for the Hugo Award and Nebula Award, is set in a society where people stand in queue for generations, with mobile "quebanas" to live in on the line.
* SocietyMarchesOn: "[[ Cocoon]]" has everyone living in virtual reality tanks a couple hundred years in the future. The husband "goes" to a virtual office and does virtual paperwork, while the wife sits at "home", does virtual housework and watches virtual soap operas all day. When the husband comes "home", he complains because the wife hasn't gotten around to punching the selector buttons for the evening nutripaste meal yet.
* SpottingTheThread: In ''Worlds of the Imperium'', the protagonist is recruited as a spy because his counterpart in an alternate universe was a ruthless dictator, and the plan was to replace his double to allow for a successful revolution. The plan works and he's successful in convincing everyone he's the dictator... up until the moment, flush with how successful the masquerade has been, he stands to greet one of the dictator's confidants and is immediately exposed. No one outside the dictator's immediate circle knew he's lost the use of his legs.
* TransferableMemory: ''A Trace of Memory''. An amnesiac alien living as a human on Earth must recover the device in which his full memories are stored. He later discovers that on his home planet almost everyone has this problem.
* VichyEarth: ''The Monitors'' is a humorous inversion. The invading aliens are actually ''extremely'' benevolent--if paternalistic--and are here to end wars and raise up mankind. They can and do provide free food, education, housing, healthcare, counseling, etc., using their SufficientlyAdvancedTechnology. Nevertheless, a whole lot of people (often inspired by [[LampshadeHanging pulp science fiction]]) immediately treat it as a Vichy Earth scenario, and start forming LaResistance.