"The oldest and strongest emotion of mankind is fear, and the oldest and strongest kind of fear is fear of the unknown."
—H. P. Lovecraft
The best known author of the Cosmic Horror Story and the origin of the Cthulhu Mythos, Howard Phillips Lovecraft (August 20, 1890 — March 15, 1937) is considered perhaps the greatest of all horror fiction writers, rivaled only by his idol Edgar Allan Poe. An antiquarian eremite, he was more fond of books than of people, very much like most of his protagonists. There is, however, no official record of Lovecraft ever encountering anything corporeally eldritch, as much as some fans wish it were all true. To this day you can find at least a half dozen different fabrications of Lovecraft's wholly fictional Necronomicon. He credited his night terrorsnote while similar to nightmares, they are actually the result of a sleep disorder with providing most of his inspiration; both night terrors and the filmy, oily membrane between waking and sleep factor heavily in his various works.Although Lovecraft had a very happy childhood by his own account — his rich grandfather, mom and aunts gave him just about everything he wanted including free run of the family library — his early years were marked by loss. His father went insane (from syphilis) and died when Lovecraft was about eight. His grandfather died and his money was mismanaged by relatives, leaving the family penniless. Lovecraft's mother also went insane and died in a mental hospital. In his adult years he drifted in and out of poverty (mostly in), ate cold beans out of cans, lost his wife, and ended his life with cancer of the small intestine.On the other hand, he was a member of the United Amateur Press Association and made many friends by correspondence, and when possible he would travel to meet them, journeying all up and down the east coast and even venturing into Canada. He was an amateur astronomer and antiquarian, a tireless walker and lover of all things ancient and strange. He was a professed atheist, but loved the gods of the Ancient Egyptians and Greeks, and as a child had prayed to them.He earned most of his living as an editor and ghostwriter. He was reluctant to sell his own stories, fearing they would not be well-received, but he was a prolific correspondent with other writers of the time, including Robert E. Howard and Clark Ashton Smith (not to mention the teenage Robert Bloch), and heavily rewrote many of their stories for them, inserting his own themes. Lord Dunsany, Edgar Allan Poe, Robert W. Chambers' The King in Yellow, and Arthur Machen are frequently cited as major influences on Lovecraft's work.No summary of Lovecraft's life is complete without a mention of his passionate devotion to cats and to his home town of Providence, Rhode Island. He only owned one cat in his lifetime, but fed and named every alley cat he found. His words I Am Providence are engraved on his tombstone.Given his view of the world, Lovecraft might be considered a real life Straw Nihilist. He was also a xenophobe, an anti-Semite and an outspoken racist; one recorded criticism of Nazi Germany was that Hitler's plans were too optimistic. 1 "The crazy thing is not what Adolf wants, but the way he sees it & starts out to get it. I know he’s a clown, but by God, I like the boy!" –Letter from Lovecraft to Donald Wandrei, November 1936 Even after he married a Jewish woman, Sonia Greene, he often made anti-Semitic remarks — in response to which she gently reminded him with whom he was sleeping. Many of his early stories and poems contained overt racial slurs, mostly aimed at immigrants from Eastern Europe and the Middle East. One of the "horrors" he intended to creep out his audience was miscegenation — racial impurity, which he considered "degenerate" — again, a commonplace societal fear at the time, especially in the New England states where opposition to interracial marriages was higher than in the South. The racial slurs are far less common in his later stories, though it's debatable whether he truly moderated his views over time - as late as 1931 he wrote: "The black is vastly inferior. There can be no question of this among contemporary and unsentimental biologists — eminent Europeans for whom the prejudice-problem does not exist."Lovecraft's stories featured not so much fear of people of different (non-White) skin colour, but distaste aimed at "mental, moral and physical degeneration" (a concept prevalent at the time) due to in-breeding, interbreeding with non-human creatures, or even immoral acts such as cannibalism. In his stories such degeneration could afflict the lower classes ("The Horror at Red Hook") and inbred rural communities ("The Dunwich Horror", "The Shadow over Innsmouth") as well as upper class families ("Facts Concerning the Late Arthur Jermyn and His Family", "The Rats in the Walls", "The Lurking Fear"). It's interesting — perhaps even humorous — to note that "The Shadow Over Innsmouth" was not inspired by fears of miscegenation, but by Lovecraft's own discovery that his great-grandmother was... Welsh.On the third appendage, Lovecraft's stories, especially the Dreamland stories, featured protagonists with dark skin of which he speaks quite highly, and Lovecraft was a great admirer of the civilizations of Ancient Egypt, Ancient Greece, and the Roman Empire. He differentiated between people of "noble" appearance and heritage and civilized behaviour contra "degenerate" individuals or tribes, independently of ethnicity or skin-colour. He thought that immigrants to the U.S. should keep their original language, dress and customs, not discard them and try to become "Americanized", because this made them look vulgar.It has often been suggested that he only incorporated so much racism in his stories because they stemmed from the element that proliferates all of his works: fear of the unknown. He almost singlehandedly invented a new cosmology, but instead of being one based on science and progress, it was instead full of otherworldly horror and blind, raving deities. While most people of his time were entranced by the technological innovation produced by the Industrial Revolution, Lovecraft was deeply suspicious of modern technology and the poorly-understood powers it vested in mankind. All of his work resonates with the terror of the newly-discovered magnitude of the universe, which in the early period of his life was believed to consist entirely of the Milky Way. Einstein's theory of relativity opened a door into teleportation, time travel, and alien geometry, and radically altered peoples' notion of space-time itself, while the discovery of pre-Cambrian fossils and Wegener's then-new-and-controversial hypothesis of continental drift brought the notion that the Earth was far older than previously believed, and that even the shape of the continents was not set in stone. All of this was subtly addressed in Lovecraft's stories of alien horror, and of the remains of ancient civilizations lost to the abyss of geological deep time.The dizzying speed of progress of his time was compounded by an expansion of the unknown. Each new development, instead of reducing the number of questions as had been expected by pre-modern philosophers, instead compounded them exponentially. Leibniz had hoped that the entire world could be described by reason, and that this is the best of all possible worlds — a possibility utterly abolished during Lovecraft's writing period. Each new discovery only increased humanity's knowledge of its own ignorance and insignificance, encouraging a nihilistic atmosphere, and this is perhaps the central theme of Lovecraft's incisive fiction. For fiction done by others in his literary mythos (and the Lovecraftian setting as a whole), see the Cthulhu Mythos.Despite some controversy over whether most of his works are genuinely public domain, they're all invariably available online somewhere. The letters are harder to get ahold of (and expensive as hell, check out Abebooks), but they're well worth the search.
Guillermo del Toro (the director of Hellboy and Pans Labyrinth) had a screenplay prepared, although it will be quite a while before anything comes of it, what with one thing and another. Although it had Tom Cruise and James Cameron involved, it was cancelled in light of The Wolfman reboot flopping. At one point, Del Toro said that Prometheus may have killed any chance of his Mountains adaptation being made, as he considers the stories much too similar, but he has since taken back this statement.
Dan O'Bannon, the original writer of Alien, is a massive Lovecraft fan (he would go on to direct an adaption of The Case Of Charles Dexter Ward) and initially conceived the plot of Alien as a kind of "At the Planet of Madness"; much of the original story involved the aliens being "gods" to a long-lost civilization who sacrificed victims to them in, and left hieroglyphs depicting their lifecycle on the walls of, a giant pyramid. Many of these ideas would be subsequently reused in Alien vs. Predator (which, just to drive the point home, was set in Antarctica) and in Prometheus.
John Carpenter's The Thing is even closer. Indeed, a genealogical connection is plausible: the film is an adaptation of John W. Campbell's short story "Who Goes There?", published in Astounding Stories in 1938. Campbell — who became editor of Astounding that year — would surely have been reading it in 1936, when it published At the Mountains of Madness. John Carpenter himself is an admitted H.P. Lovecraft fan, so it'd hardly be surprising if he drew a little inspiration from the story, even indirectly (there actually is some resemblance between the sequences where Mac and Copper investigate the Norwegian camp in The Thing and the scene where Dyer and Danforth investigate Lake's camp in At The Mountains of Madness, not to mention that the Norwegians weren't in the novella the film was based on...). He even made In the Mouth of Madness as a tribute to Lovecraft's work.
Filmed in 1970 as a not-entirely-faithful Cult Classic starring Dean Stockwell and Sandra Dee. Yog-Sothoth! There was also a 2009 remake by the SyFy Channel - again starring Dean Stockwell.
"The Colour Out of Space" — A toxic meteorite that's of a colour Not of This Earth devastates a small farm in Massachusetts. Lovecraft insists upon using the Commonwealth spelling of "colour", as always. He stated that this was his favorite of all his stories.
A big part of the inspiration for the "Weeds" segment (starring self-professed Lovecraft fan Stephen King) in Creepshow.
King himself has said that The Tommyknockers derives part of its premise from "Colour;" the story's protagonist, Gardner, shares his name with the hapless farmer of the earlier story.
Plot also used in the movie The Curse, starring John Schneider, Claude Akins, and Wil Wheaton. Rather faithful to the original, under the circumstances.
Also a very loose adaption from 1965 called Die, Monster, Die! with Boris Karloff.
Adapted in 2008 as movie called Die Farbe (The Colour) by Sphärentor Produktion, a German indie studio. All in black and white, except for the colour itself. Makes a few changes, but overall pretty faithful to the source material.
"The Shadow out of Time" — One of his best-regarded stories. A strange creature from the deep past swaps bodies with a modern-day scholar, followed by the latter's subsequent investigations into the years he can't remember.
Adapted as a short old-timey independent film and released in 2012. See it here.
Has been adapted a number of times into short movies by various independent film makers from different countries, movies which were collected on DVD as part of The H.P. Lovecraft Collection (Part 4) by Lurker Films, Inc.
"Cool Air" — A boarding-house resident who likes, for some reason, to have it very cold in his apartment goes into a panic when his swamp cooler breaks down; his next-door neighbor soon begins to wonder where the smell is coming from...
"Cool Air" and "Pickman's Model" were made into episodes of Night Gallery. Unfortunately, Night Gallery insisted on adding a female love interest and Damsel in Distress for Pickman to the episode. Not only that, the story was combined with "Innsmouth", only with rats instead of fish.
Also was loosely adapted as one of the segments in the cheaply-made, only nominally Lovecraftian anthology film Necronomicon, with, of all people, a slumming David Warner as the star. They decided to throw in a love triangle plot, for some reason.
A quite faithful indie adaption of "Cool Air" can be found in The H.P. Lovecraft Collection (Part 1) by Lurker Films, Inc.
Adapted as "Baby, It's Cold Inside" in Vault of Horror #17 (February 1951) from EC Comics.
"The Rats in the Walls" — The narrator, a man from New England, buys an old keep in England that belonged to his ancestors (and which was erected at the site of much older Roman and iron-age temples) and discovers a horrifyingfamilysecret that drives him insane.
"The Whisperer in Darkness" — A science fiction First Contact story with strong horror elements. A scholar and his pen pal friend discover a colony of sinister fungoid space-faring aliens in the mountainous rural backwaters of Vermont in 1930.
His Dreamland stories, among them "The Cats of Ulthar", "The Silver Key", "Through the Gates of the Silver Key" and The Dream-Quest of Unknown Kadath. The last encompassed a number of characters from Lovecraft's other stories, "Pickman's Model" in particular.
Herbert West — Reanimator — A Mad Scientist develops a serum that can revive the dead. Probably best known in its gory, darkly comedic film adaptation it is actually one of the first tales to use the cannibalistic zombies archetype so beloved of modern culture. The novella itself was written as a parody of Frankenstein. Lovecraft himself disliked the story due to the constraints placed on him by the magazine in which it was published.
"The Music of Erich Zann" — A student, seeking cheap accommodation, takes a room underneath a strange, mute cellist who plays unnatural music late into the night. He considered this one of his best stories, as he managed to avoid his usual tactic of explaining everything (read: the tiniest explanation of anything is not even alluded to other than on a paper the protagonist never gets to read).
"Dagon" — A young man serving in the navy during World War I escapes German captivity only to glimpse a strange monster.
"The Temple" — A German U-Boat crew is subjected to a series of strange and unexplained events.
Apart from these, the H.P. Lovecraft Historical Society and other fan groups have produced A Shoggoth on the Roof, a musical based on the Cthulhu mythos (the initial score was that of Fiddler on the Roof, but it was modified after lawsuits). Considering Lovecraft's aforementioned anti-Semitic leanings, this is actually rather hilarious.
For a mostly-complete list of film adaptations, see Lovecraft on Film. For the comic book about Lovecraft, see Lovecraft.The YMMV page for his collective works can be found here.
Ancient Astronauts: Perhaps the first use of the trope in fiction. Notable in that unlike most ancient astronaut stories, the aliens are decidedly not humanoid, and have no interest whatever in humanity.
And Then John Was a Zombie: Happens in "Shadow over Innsmouth", and played with in "The Whisperer in Darkness" (Akeley does not actually become one of the creatures, but he does join their community, as it were). Pickman's alluded-to fate (later confirmed in The Dream-Quest of Unknown Kadath) in "Pickman's Model" is an inversion: he does not, in fact, consider it a terrible fate at all.
And Randolph Carter, featured in several Lovecraft's best-known tales. A WWI veteran, having served from the first in the Foreign Legion of France, he has great courage and resourcefulness despite his occasional tendency to swoon when things get too eldritch.
Badass Normal: A strange non-human example. The Elder Things, despite being ordinary carbon-based lifeforms instead of being made of extradimensional exotic matter like most of the gibbering horrors of the Cthulhuverse, actually managed to survive a fight against the big green himself.
Based on a Dream: Not only were many of Lovecraft's stories based on dreams he had, but the characters within his works often created art or writing based on their dreams.
"The Shadow Over Innsmouth" has the Innsmouth people's gradual "degeneration" into increasingly fish-like forms. It's mentioned that some of the older residents have become so deformed they can't even go outside anymore.
"The Colour Out of Space" has shades of this as well, with the colour's influence gradually disintegrating the bodies of the afflicted.
Bowdlerize: "Nigger-Man," the cat from "The Rats in the Walls" (named after Lovecraft's own, we might add), is never called what it was in the original story in adaptations. The closest anyone's dared get was in the 1972 Skull Comix version, where it's "Nigaman".
British English: Wrote in this dialect, despite being American, using words like "torch" for "flashlight."
Big Bad: Plenty of them per story, but the most notable ones are Elder/Outer Cthulhu, Azathoth, and Yog-Sothoth, all of whom are essentially powerful enough to destroy the known universe (Cthulhu being the only one bound to Earth, which he shall destroy in Lovecraft's universe). Asenath Waite or rather, her father Ephraim can be considered the Big Bad of "The Thing on the Doorstep", as can Nyarlathotep for The Dream-Quest of Unknown Kadath.
Brick Joke/Unpaused: In "The Shadow Out of Time" the narrator loses consciousness while giving a lecture at the beginning of the first chapter. At the end of the chapter and several years later he wakes up muttering about economics.
Cannibal Larder: In the short story "The Picture in the House," the narrator realizes that his host's talk of historical cannibalism is not purely academic when blood soaks through the ceiling and drips onto the titular picture.
Cats Are Magic: In Lovecraft canon, specifically The Dream-Quest of Unknown Kadath, the cats of the Dreamlands can travel to the Moon on their own power and have a secret language. They worship Bast and aid the hero in his quest. The only thing the Earth-cats fear are the cats from Saturn, who are even more powerful than they, but are in league with the Eldritch Abominations.
City of Gold: Several of the Dreamlands' cities are described in terms of the exotic and precious materials from which their streets, wharfs, or buildings are made.
Cosmic Plaything: Several of his protagonists qualify. Lovecraft's own life comes across as this, which probably contributed to his use of the trope.
Crapsack World: Almost goes without saying, and in line with Lovecraft's nihilistic worldview.
Creator Provincialism: Much of his work takes place in New England due to being raised in Providence, Rhode Island.
Creepy Child: Wilbur Whateley, the Villain Protagonist of the first part of "The Dunwich Horror", is described to be very creepy (both visually, and from his behaviour; he actually is much much much younger than he looks) by all his neighbours and the people he meets. When he dies, it is revealed from a quick look on his half naked corpse that he actually is an Humanoid Abomination which bottom part isn't even remotely human looking. He actually is the hybrid child of the Old One Yog-Sothoth and a Dunwich sorceress.
Devil in Disguise: At the end of "The Whisperer in Darkness", the Henry Akeley whom the narrator speaks with is implied to have been a Mi-Go (or one of their sympathizers) in disguise while the real Akeley had already become a Brain in a Jar.
Most notably, the monster beneath "The Shunned House" is killed by pouring sulfuric acid over it.
There is also the trio of Miskatonic professors, who went and kicked the Dunwich Horror's ass and sent him crying to his dad. Literally.
And we can't really forget Gustaf Johansen, who actually did attempt to punch out the actual Cthulhu by charging a steam ship at him. OK, so Cthulhu reformed immediately, his friend went mad and he ended up dead thanks to Cthulhu's cult, but A for effort.
Downer Ending: At the end of the majority of his stories the protagonist dies, becomes insane, or loses (or several of the three). Some have bleaker endings: The protagonist actions has no importance whatsoever and they remain sane, now with the knowledge of all the horrors that exist.
Dream Land: Lovecraft's Dream Cycle stories, inspired by the works of Lord Dunsany, are set in a world which can be entered through dreams. The Dream-Quest of Unknown Kadath suggests that each planet has its own dream land, and there are some locations where the dream land and waking world intersect.
Evil Is Visceral: Many things are "squamous," which means scaly or looking like a close-up of a layer of skin cells.
Evil Smells Bad: There are plenty of references to the stink of evil things and to "charnel" or "putrid" atmosphere in haunted places. For readers of the inter-war years, many of which had some war experience and lived in an age with poor garbage management, this was even more sinister.
"Wisely did Ibn Schacabao say, that happy is the tomb where no wizard hath lain, and happy the town at night whose wizards are all ashes."
Similar concept, different execution. In The Case Of Charles Dexter Ward, a repeated theme and instruction is to refrain from killing the necromancer villain with fire, as he can be resurrected from the ashes. Instead, the protagonist is instructed to dissolve the body in acid.
For the Evulz: Nyarlathotep, one of the few Eldritch Abominations who seems to take active interest in humanity, seems to love messing with people just because he can. Although in some stories he is simply the guardian of hidden lore, in The Dream-Quest of Unknown Kadath, he's intentionally cruel. In the prose poem "Nyarlathotep," he tours the country driving people insane with scientific exhibitions. His purpose is never clear. In general, he's so powerful that his cruel actions are analogous to a child burning ants with a magnifying glass.
The Great Race of Yith (aka the Yithians) have this as their hat. When faced with a danger they cannot overcome, they will, as a group swap bodies with another race of beings at some other place and/or time to escape, leaving the minds of those they switch with to perish in their previous bodies. It should be noted that these are among the nicer being inhabiting this universe, as they actually notice humans and don't destroy or enslave us as an automatic reaction.
An unusually unnatural version, even by the standards of Lovecraft, the man-made anthromorphic animal mummies from Under The Pyramids, created in a blasphemous ritual to emulate the Egyptian pantheon, and rejected by all sane divine forces.
Heterosexual Life-Partners: One of Lovecraft's favorite tropes. Examples include Edward Derby and Daniel Upton, Herbert West and his Watson-esque assistant, Walter Gilman and Frank Elwood, St John and The Hound's anonymous narrator, Randolph Carter and Harley Warren, the dudes from Hypnos (though their case borders on Chastity Couple)... Thurber might have had such a relationship with Richard Pickman if not for realizing how insane he was.
Hollywood New England: Lovecraft was a Yankee Patrician to the core. He famously proclaimed "I am Providence."
Infant Immortality: Notably averted: While children are a rarity in Lovecraft's fiction, chapter three of Herbert West—Reanimator mentions a missing child who is strongly suggested to have been eaten by West's latest zombie creation. In "The Dreams in the Witch House", the protagonist Gilman fails in his attempt to save a kidnapped child from the witch and her familiar.
Inspired By: The house from "The Shunned House" actually exists, as did Jacques Roulet, the psychotic French 'lycanthrope' from the short story. Of course, the two never really had anything to do with each other, and H.P. Lovecraft only chose to write about the house because it was pretty creepy looking.
In the Blood: Many of Lovecraft's protagonists are doomed to commit their ancestors' crimes and suffer from their insanity.
It's the Only Way to Be Sure: In a surprisingly large number of stories (The Picture in the House, The Lurking Fear, The Shadow Over Innsmouth and The Rats in the Walls among them) Lovecraft's solution to the inconceivable threat of the dark power of the abyssal gods is to just blow it up.
Irony: As stated above, he had anti-semetic views earlier in his life, yet he married a Jewish woman.
Jerk Ass Gods: Nyarlathotep is a dick. See the ending of The Dream-Quest of Unknown Kadath. The other Lovecraftian deities aren't really jerks as they don't even notice our existence.
Kindhearted Cat Lover: Randolph Carter is described in The Dream-Quest of Unknown Kadath as loving small black kittens more than anything in the world. This works to his advantage when he gets kidnapped by aliens.
"The Thing on the Doorstep" definitely uses it. The narration points out that though the hero is celibate, book-wormish, obsessed with late hours and forbidden topics, he has as yet not seen any abomination capable of destroying his sanity.
"The Unnamable" is kind of a spoof of Lovecraft's own tendency towards making his monsters indescribable, incomprehensible, or, indeed, unnameable.
Long Title: "Facts Concerning the Late Arthur Jermyn and His Family". To Lovecraft's distaste, it was retitled "The White Ape" when it was first published. Simply shortened to "Arthur Jermyn" in the Del Rey anthology.
No Hugging, No Kissing: His stories didn't feature any romantic subplot (nor, most of the time, female characters).
Nothing Is Scarier: Lovecraft was of the opinion that "the oldest and strongest kind of fear is fear of the unknown." "The Music of Erich Zann" is perhaps his best example; the horror of that story lies not in any kind of monster, but a vague sense of something horrible and unknowable lurking outside the window.
Or Was It a Dream?: The narrator of Under The Pyramids belives what he saw beneath the pyramids was just a mad dream brought on by his obsessive reading of egyptology prior to his trip and the trauma he endured leading up to him being trapped inside the tunnels but part of him cannot forget that his mysterious guide that no one else seems to remember, had a disturbing likeness to Pharao Khefren, the face upon the Sphinx.
Our Ghouls Are Different: Lovecraft popularized his own version of ghouls as a secretive living species, rather than undead or demons.
Pet the Dog: The Yithians may be body-snatchingStarfish Aliens, but that doesn't stop them giving their victims balloon rides. In fact they go to some lengths to make their un-consenting guests' stay comfortable and interesting.
Posthumous Narration: "The Picture in the House" ends with the narrator discussing how the house was struck by lightning, killing him and the old man.
Puny Earthlings: Humanity are completely outclassed by every alien race in the Mythos. This trope was kind of the point of most of Lovecraft's writing, really.
Purple Prose: In this case it's purple in the sense that an oozing infected bruise is purple. Fans enjoy it as part of the appeal.
Ragnarok-Proofing: Ruins of both the unbelievably old Elder Thing and Yithian civilizations — even books for the latter! — have been found remarkably intact, though usually by being sealed away deep beneath the Earth where they cannot be worn away by weather or nature.
Redemption Equals Death: Or possibly, Redemption Requires Death - although it's ambiguous. In "The Horror at Red Hook", the corpse of Robert Suydam reanimates itself somehow and pushes a golden pillar into the ocean, severely disrupting a cult/smuggling ring's operations.
Religious Horror: Many of Lovecraft's more Mythos-focused works fall into this, by a weird mixture of God Is Evil and "Atheistic Horror" — that is, the presentation of the universe as being devoid of any higher power and humans as being no more special than any other lowly beast. Yes, the latter isn't so scary nowadays, but people were a lot more religious in Lovecraft's time — it was a truly terrifying thought in those days, that humans did not have The Almighty championing them and giving them dominion over the Earth.
The existance of Azatoth is almost worse than the concept of God Is Evil. The creator of our universe is little more than a mindless force, with no ability to care one way or the other about the goings on of its creation. He is not good or evil or even just alien like the Elder Gods, he simply Is.
Science Marches On: At the time Lovecraft was writing based on the latest science of the day, and strove for accuracy. Nevertheless, scientific progress has since overtaken him:
Lovecraft identified the Semitic god Dagon with his Deep Ones, based on a then-widely-accepted etymological link to the Hebrew word for "fish". Modern anthropologists consider this a coincidence, and the historical Dagon is now believed to have been a god of agriculture.
The stories "The Colour Out of Space" and At the Mountains of Madness are also heavily affected by eighty years or so of progress since they focus on scientific investigations of strange phenomena. Most notably the fact that there are no Alien Geometry mountains or giant, albino penguins in Antarctica - darn it.
Whenever referring to human evolution, one of the first hominids to be mentioned is Piltdown man, which, of course, turned out to be a hoax.
On the other hand, progress has sometimes backed Lovecraft up on matters that were mere speculation in his day: For example he supported and included the Continental Drift Theory in his stories, which is of course widely accepted nowadays but was then rejected by most scientists. Also, he wrote about a ninth planet in our solar system mere months before Pluto was discovered.
Clark Ashton Smith, Harry Houdini and some of Lovecraft's other friends became characters in his stories.
Robert Blake in "The Haunter of the Dark" is modeled on Lovecraft's young admirer Robert Bloch. There's also a character named Howard who is a recluse in Providence ends up dying in one of Bloch's stories. "The Haunter of the Dark" even references that story. Both stories also begin with dedications to the other author, and involve the other dying horribly.
"The Shadow Out of Time" mentions Crom-Ya, a barbarian chief who lived around 15,000 B.C. This is a homage to Conan the Barbarian, Robert E. Howard's most famous character.
Edgar Allan Poe was a major influence, and references to his stories can be found throughout Lovecraft's work. "The Shadow Over Innsmouth" borrows several terms and phrases ("imp of the perverse," "conqueror worm," etc.) directly from Poe, and "The Call of Cthulhu" features a Scandinavian sailor whose hair turns white after a terrifying incident at sea, much like the protagonist in "A Descent into the Maelström.” There are also significant parallels between At the Mountains of Madness and Poe’s only novel, The Narrative of Arthur Gordon Pym of Nantucket.
"The human figure is as worthy a type of subject-matter as any other object of beauty in the visible world. But I don't see what the hell Mrs. Brundage's undressed ladies have to do with weird fiction."
Spell My Name with a Blank: In "The Alchemist", written in Lovecraft's late teens, the narrator's last name is blanked out; he only refers to himself as "Antoine de C-".
Stealth Parody: Reanimator was a work of commissioned Frankenstein ripoff that Lovecraft was doing for the cash. By the last few chapters, it's increasingly apparent that Lovecraft was just going "Fuck it" and purposefully making it as absurd as possible.
Starfish Aliens: The Elder Things, the Mi-Go, the Great Race of Yith, and many others.
Surprisingly Sudden Death: Pretty much anytime Cthulhu shows up. Most notably in "The Call of Cthulhu" when the sailors stumble upon the non-Euclidean structure in the sea. One of them climbs on and prods it for a bit; a tentacle reaches out, grabs him, and devours him. The rest soon follow and only two sailors survive, one of whom goes batshit insane from looking at Cthulhu. A boat injuring Cthulhu proves enough of an inconvenience to stuff him back in the can, averting the end of days.
Take That: New York. Lovecraft hated New York and made it apparent. If you want to know what he thought of New York, read "He".
Then mankind would have become as the Great Old Ones; free and wild and beyond good and evil, with laws and morals thrown aside and all men shouting and killing and revelling in joy. Then the liberated Old Ones would teach them new ways to shout and kill and revel and enjoy themselves, and all the earth would flame with a holocaust of ecstasy and freedom.
Troll: When he found a student mistaking the abbreviation "ibid." for the name of some famous ancient Roman Lovecraft found this so funny that he went and wrote a whole story about Ibid just to mock the student.
The shoggoths in At the Mountains of Madness, and the reanimated corpses (if the men that created them could be called "masters") in Herbert West - Reanimator.
Joseph Curwen was killed for the first time, at least, when he lost control of his "guardians".
Uncanny Valley: Used extensively In-Universe. If the antagonists are "human", expect the narrator to describe them as "strange" and make reference to "peculiar alterations".
The Unpronounceable: Lovecraft loves names that are nigh-unpronounceable due to the fact that they were not intended for humans to speak. His most popular name is Cthulhu. Lovecraft transcribed it as either "Khlûl'hloo" or "Kathooloo"; fans often use "Kuh-THOOL-hoo". Then again, even the pronunciations described by Lovecraft were said to be the closest approximation of the true name human vocal ability could produce. So, in essence, any human saying it can never pronounce it right.
Unreliable Narrator: A lot of the first-person narration in his stories either become more maddened as it progresses, or has the narrator repeatedly questioning his own sanity and memories.
A staple of most Lovecraft stories; the narrators almost always attribute the strange events that happen to them and others they correspond with as explainable by their overactive imaginations and dreams, right until the end of the stories where they are confronted by the undeniable hideous truth and often Go Mad from the Revelation.
A prime example of this is "The Nameless City" wherein the narrator attributes the wall-art showing the lizard/seal things to be symbolic of early humans and/or the gods they worshiped. Even after seeing wall-art of the lizards killing a human, it takes a while for the point to sink in.
Zombie Apocalypse: In Reanimator, they're close to Romero zombies, right down to the spine being the weak point, akin to regular zombies having the head as the weak point. Notable because it was published decades before Romero became famous, as a Frankenstein parody.