Horrorterror

The Noble Circle of Horrorterrors lead the mysterious eldritch creatures that reside in the Furthest Ring. These creatures seem to be getting HS 4939 (massacred by an unknown source), later HS 7288 (shown) to be, causing them to reach out to Sburb players. They whisper to the dreamers of Derse during the eclipse and have been seen enlisting Rose and Dave. They serve as a Derse player's advantage, equivalent to Skaian Clouds on Prospit. Feferi's Lusus, Gl'bgolyb, is referred to as an "emissary" to them.

They appear to have some sort of suspicious and mysterious agenda, but their involvement in Sburb remains unknown to this day. They seem to be opposed to the creation of new universes (although this may only apply the humans, who created the universe  was born in), but also to the complete destruction of reality. The horrorterrors are inspired by H. P. Lovecraft's Cthulhu mythos and are in fact referred to as Outer Gods at several points.

On Earth, the Squiddles are a subconscious re-imagining of the horrorterrors and other Beasts residing in the Furthest Ring, with the character Skipper Plumbthroat possibly representing.

Known horrorterrors include Gl'bgolyb, Fluthlu, Nrub'yiglith, and Oglogoth.

Nrub'yiglith
Nrub'yiglith is found in Rose's Grimoire for Summoning the Zoologically Dubious. He is seemingly of a higher order than the better known Fluthlu; a size comparison reveals that, even next to to the already gigantic Fluthlu, he is monstrously huge. However, he is also shown to be tiny in comparison to the "smallest of the Smaller Gods," Oglogoth. He bears a startling resemblance in both name and appearance to Gl'bgolyb, Feferi's lusus (with an equally impronounceable name). His name also bears a (less startling) resemblance to the names of several eldritch beings from H.P. Lovecraft's Cthulhu Mythos, such as Shub-Niggurath, "The Black Goat of the Woods with a Thousand Young," and Yig, "Father of Serpents," as well as "the Twin Blasphemies," Nug and Yeb. This matches Fluthlu 's obvious allusion to Cthulhu himself.

It is possible that Nrub'yiglith is the kids' universes' version of Gl'bgolyb, existing somewhere within their universes. However, he may also dwell in the Furthest Ring, serving the Noble Circle of Horrorterrors and their underlings.

Oglogoth
Oglogoth is found in Rose's Grimoire for Summoning the Zoologically Dubious. The Grimoire describes him as. Whenever he grinds his teeth, all the children of a random galaxy somewhere will frown continuously for a nine thousand year span. He is the first and smallest of the SMALLER GODS, appointed in servitude of a vile, unfathomable pantheon of MIDDLING GODS which caters to the whims of the Noble Circle of Horrorterrors, an omniscient, omnipotent order of the elite few, forever cloaked in the darkness of the Furthest Ring.

He dwarfs Nrub'yiglith, who in turn looms over Fluthlu, so the scale of this creature is near unimaginable, and he is apparently the smallest of the smaller gods. Good thing the Grimoire is in the hands of a young lady with such a good head on her shoulders.

He is the patron of the fearsome Thorns of Oglogoth, which Rose obtains by combining her Needlewands and the Grimoire.

Player Contact
When a player goes to sleep after their dream self dies, they are free to come into close contact with the horrorterrors via the afterlife. Feferi, due to her positive connection with Gl'bgolyb, manages to talk them into "glubbing up" a series of stabilized dream bubbles that serve as a communication tool between the trolls and the kids, as well as the dead and the living.

As Jack Noir and the prototyped Peregrine Mendicant flew through the Furthest Ring, they seem to be able to come into physical contact with the horrorterrors, but are either possibly unable to interact with them or too busy fighting to concern themselves with them.

Grimdarkness
On LOHAC, Rose was persuaded by to ask the Magic Cue Ball if the horrorterrors were evil. The response was HS 005539 (lines of meaningless incoherent text) (except for the phrase "Oglog M'Rubbit," a ). Upon viewing this answer, she went Grimdark, an uncontrollable and horrifying process described as going. This physically caused Rose to develop darkened skin, glowing eyes and a thorny black aura reminiscent of the horrorterrors' tentacles, and begin speaking in an incomprehensible language.

During her fight with Jack she seemed to be able to manifest her aura into HS 5686 (actual physical thorns.)

This can be interpreted as Rose losing control over the dark magic she received from the Circle. It could also be the result of a sudden surge of power granted her by the horrorterrors. Rose died shortly thereafter and was replaced by her dream self, yet the physical changes were not present on her dream self.

The word 'Grimdark' seems to have originated in the table-top game, Warhammer 40,000 and evolved into a memetic phrase.

It is currently speculated that a parallel to this power through the use of a combined cherub Juju is Trickster Mode, as seen when Jane HS 7612 (caused a world-changing explosion and flew away) shortly after HS 7611 (engaging the transformation). While Rose's Grimdarkness is black, frightening, and out of control, Jane's Trickster Mode appears to be the exact opposite, being bright, silly, and even more so out of control. Also as Grimdarkness is HS 5542, Trickster Mode is called HS 7678.

Trivia

 * Andrew Hussie has     the Alternian universe was played by 48 Squiddles and that he shall reveal these characters and/or kill them soon. It should be noted that the Alternian universe has a HS 4475 (48 sign horoscope) suggesting that the Sburb session that created it did indeed have 48 players, that The Ultimate Reward of Sburb is to create a new universe and then inhabit it whilst repopulating, and that Squiddles and horrorterrors are often treated synonymously (such as in HS 4748 (Jade's dream), or HS 7614 (Jane's trickster mode)). Coincidentally, horrorterrors (sometimes addressed as gods) are, in fact, currently being killed off (by ). However, whether the horrorterrors are the previous players (or the offspring of those players) and creators of the Alternian universe or simply game constructs like denizens and carapaces is yet to be seen.
 * Their blood color, as seen in "HS 7161 (Caliborn: Enter)" and "HS 7163 (Act 6 Intermission 3)", lies between Eridan's and Gamzee's, with the hue being closer to Purpleblood than Violetblood.