It was a terrible, indescribable thing vaster than any subway train—a shapeless congeries of protoplasmic bubbles, faintly self-luminous, and with myriads of temporary eyes forming and un-forming as pustules of greenish light all over the tunnel-filling front that bore down upon us, crushing the frantic penguins and slithering over the glistening floor that it and its kind had swept so evilly free of all litter.
—H. P. Lovecraft, At The Mountains of Madness
The definitive description of shoggoths comes from the above-quoted story. In it, Lovecraft writes them as massive amoeba-like creatures made out of iridescent black slime, with multiple eyes "floating" on the surface. They are described as "protoplasmic", lacking any default body shape and instead being able to form limbs and organs at will. An average shoggoth measured fifteen feet across when a sphere, though the story mentions ones of much greater size.
Mythos media most commonly shows them, although intelligent to some degree, dealing with problems using their great size and strength. For instance, the original one mentioned in At the Mountains of Madness simply rolled over and crushed giant albino penguins that were in the way as it pursued the characters.
The character of the Mad Arab, Abdul Alhazred, found the mere idea of their existence on Earth terrifying as many characters from Lovecraft's stories do.
Origin and history
The shoggoths were created by the Elder Things. Being amorphous, they could take on any shape needed, making them very versatile within their aquatic environment. Though able to "understand" the Elder Things' language, they had no real consciousness and were controlled through hypnotic suggestion.
The shoggoths built the underwater cities of their masters. Over millions of years of existence, some shoggoths mutated and gained independent minds. Some time after this, they rebelled. Eventually, the Elder Things succeeded in quelling the insurrection, but thereafter watched them more carefully. By this point, exterminating them was not an option as the Elder Things were fully dependent on them for labor and could not replace them. It was during this time that, despite their masters' wishes, they demonstrated an ability to survive on land.
Within the Mythos, the existence of the shoggoths possibly led to the accidental creation of Ubbo-Sathla, a god-like entity supposedly responsible for the origin of all life on Earth, though At The Mountains of Madness brings up the possibility of the Elder Things being the creators, having made early life as discarded experiments in bioengineering.
When the Elder Things retreated to the oceans, they took the shoggoths with them, but also out of desperation let them develop the ability to exist on land. In contrast to their failing society, the shoggoths began to imitate their art and voices, taking over the cavern city underneath Antarctica and creating a twisted imitation of the society of their masters.
Aside from their main appearance in the Mountains of Madness story, shoggoths also appear in other Mythos stories, often as servitors or captives to powerful cults and entities. They are known to endlessly repeat "Tekeli-li", a cry that their old masters used.
Shoggoths play a prominent role in Edward Lee's 2009 novella "Haunter of the Threshold." However, Lee's depiction of Shoggoths is significantly different in that they're generally humanoid in shape with upside down facial features that are deformed when compared to those of a human, suctioned tentacles for their arms with thicker tentacles for legs, one massive tentacle-like structure to serve as a torso and fully functioning genitals, including a penis two feet in length. In the novella, Shoggoths are portrayed as sexual deviants belonging to a cult, along with similarly deviant humans, who worship Yog-Sothoth. The ultimate goal of the cult is to bring the Outer God to Earth.
A monster identical to a Shoggoth appears in The Illuminatus Trilogy where it consumes crime lord Robert Putney Drake as a punishment for him switching allegiance.
A Shoggoth appears in the game Call of Cthulhu: Dark Corners of the Earth, where it lurks in the sewers of Innsmouth before being encountered in the Marsh Gold Refinery. The Shoggoth is treated as a protracted boss encounter and cannot be injured with the player's weapons.
Shoggoths appear in the penultimate and final novels of Edward M. Erdelac's weird western series Merkabah Rider.
Shoggoths make an appearance in the Dwarf Fortress mod "Masterwork" as an enemy creature that appears during mining.
^This spelling appears in the original Arkham House printing for "The Thing on the Doorstep" (1937 or shuggoth), though the definitive manuscripts show that the proper spelling is in fact "shoggoth". (Burleson, H.P. Lovecraft, A Critical Study, footnote #14, p. 195.)
Burleson, Donald R. (1983). H. P. Lovecraft, A Critical Study. Westport, CT / London, England: Greenwood Press. ISBN0-313-23255-5.
Harms, Daniel (1998). "Shoggoths". The Encyclopedia Cthulhiana (2nd ed. ed.). Oakland, CA: Chaosium. pp. 273–4. ISBN1-56882-119-0.
Lovecraft, Howard P. (1985) . "At the Mountains of Madness". In S. T. Joshi (ed.). At the Mountains of Madness and Other Novels (7th corrected printing ed.). Sauk City, WI: Arkham House. ISBN0-87054-038-6. Definitive version.
Pearsall, Anthony B. (2005). The Lovecraft Lexicon (1st ed. ed.). Tempe, AZ: New Falcon Pub. ISBN1-56184-129-3.