At the Mountains of Madness is a 1936 novella by H. P. Lovecraft, serialized in Astounding Stories magazine. It revolves around the geologist William Dyer, leader of an expedition to Antarctica. While digging for ice cores, his team uncovers the frozen bodies of creatures of indeterminate origin; later, most of the expedition is mysteriously slaughtered. Dyer's party discovers the ruined camp, and he and a graduate student fly over the mountains into mystery to investigate further. They soon find themselves beyond massive mountain peaks, in the ancient ruins of a colossal city, completely alien in design...A film adaptation, directed by Guillermo del Toro and produced by James Cameron, was in the works, but was cancelled after the failure of the Wolfman reboot. However there has recently been talk about revisiting the project.It can be read here.
Author Phobia: Lovecraft's life-long fear of cold temperatures is part of what makes this story so effective.
Badass Normal: And odd example, but the Elder Ones certainly fit. All of them. Although not human by any means, they were carbon based lifeforms, that, without any supernatural powers or anything similar, led a war against Star Spawn and their god/priest Cthulhu, and won. Sure, it was more of a stalemate than anything else, but still...
Bizarre Alien Biology: And how! The Old Ones apparently had gills, lungs, tentacles, wings, and numerous mouths, among other things. They seem to reproduce asexually and have massive, if not indefinite, lifespans, in addition to massively resistant bodies and nigh-impossible endurance (since they survived having been frozen for aeons).
Note that, as far as Lovecraftian beasts go, they're stated to be a species of Badass Normals, since despite their biological superiority to humans, they made little or no use of magic (unlike the Deep Ones), were constrained by time (unlike the Race of Yith) and had bodies made of "regular" matter (while the Mi-Go and Star Spawn of Cthulhu were explicitly stated to be more exotic).
Doing in the Wizard : Many elements of previous stories in the Cthulhu Mythos are recast as being of extraterrestrial, as opposed to supernatural, origin. Another interpretation is that he protagonist of the story was a scientist, and the Old Ones seem very science-based themselves. It could just be a case of the protagonist, the old ones, or both trying to explain where the creatures of the Cthulhu Mythos came from. With science.
Downer Ending: Lake's entire party is killed by Elder Things. On top of that, Danforth has probably gone insane, and Dyer is trying to stop a second arctic expedition from taking place, and chances are no one will believe the reason why. But hey, it's Lovecraft, what did you expect?
Harmless Freezing: The Elder Things were frozen for a long period of time. When they're thawed out they go on a murderous rampage (understandably since several of them had been autopsied by the humans, possibly while still alive but not thawed enough to move.) The freezing and surviving is justified in that they are described as being extremely tough in comparison with humans.
"Radiates, vegetables, monstrosities, star-spawn - whatever they had been, they were men!"
This is especially exceptional for Lovecraft's stories, where most things that are "different" are usually "wrong". The Elder Things are the most "human" and benign of the Mythos species. Aside from their strange biology and amazing toughness, they are made of mundane elements (compare with the Mi-go, or the partly-spectral flying polyps), they formed family units, and had an art-producing culture and an economy. Perhaps most importantly, they only lashed out at the human party in horror and vengeance for the humans mutilating them first, rather than out of sheer carelessness or malice.
Panspermia: Of a sort: according to this story all life on Earth started with experiments the Old Ones let live out of apathy. So in other words, we're all the spawn of failed alien bioengineering.
The leathery, undeteriorative, and almost indestructible quality was an inherent attribute of the thing’s form of organization, and pertained to some paleogean cycle of invertebrate evolution utterly beyond our powers of speculation.
Science Marches On: The past seventy-five years have shown many advancements in Antarctic exploration, revealing a continent wholly unlike what is described in this book.
Some of the terminology, such as "Comanchian", was already obsolete. So was the initial idea (edited out of the final product) that Antarctica was actually two continents.
There was also the very concept of interplanetary travel; they were said to "fly through the aether on leathery wings", with the "luminiferous aether" being the old concept of what existed beyond the upper atmosphere. The concept of space as a near-complete vacuum was becoming prominent in Lovecraft's time, and theories about the luminiferous aether dying out, after an experiment disproved the idea that light couldn't pass through a vacuum, but he was swayed by the lecturing of a theorist he held in high regard.
However, it must be noted that this is a third person interpretation of an ancient (silurian era) pictographic carving by a race of aliens with minds that work differently than humans', and therefore may be a complete misinterpretation of the actual events depicted, if you want to strap on your Watsonian hat.
And of course, we now know that no mountain in Antarctica reaches thirty-five thousand feet.
Sickly Green Glow: Shoggoths are described by Dyer as enormous black masses of protoplasmic bubbles covered in luminescent green eyes that are constantly forming, shifting around and dissolving.
Slave Race: The Shoggoths, to the Elder Things. Shoggoths were not originally created to be sentient: they were more like bioengineered construction equipment, and only became sentient through unintended mutations.
Starfish Aliens: The Elder Things are radially symmetric and built around pentagon and five-pointed star shapes. Shoggoths are just Blob Monsters.
Starfish Language: Elder Things communicate by making piping sounds through their breathing tubes.
Unreliable Expositor: Dyer considers the possibility that the Elder Thing's histories may be colored somewhat. He wonders if the “exotic matter” of the Star-spawn and Mi-go is a mythological construct, and notes that there is no mention of the Great Race of Yith.