Daelkyr

Daelkyr are insane totally-not-Lovecraftian Outsiders from Xoriat, the realm of madness. They invaded the Eberron something like 9000 years ago for reasons unknown to anyone (probably including themselves) and caused one of the most horrific conflicts in the history of Khorvaire. While few in number, daelkyr are powerful to an almost godlike degree, capable of reshaping reality on local level, reforging the forms and minds of creatures with a thought, barely contained by time and space so they don't really move in the way sane creatures can comprehend, looking like they teleport (they don't, they time-travel to move, don't ask how). And yet they are technically mortal and could be killed. Which is actually an advantage in Eberron cosmology, as all true immortals are unchanging and cannot learn. Daelkyr can and do learn and change, which makes them even more dangerous. No one knows what they really look like - those who've seen them described them as angelically beautiful humanoids clad in living armour, but everyone sees them as members of their own race. Some tried looking on them using True Sight to pierce through this glamour and every one of them instantly went insane.

Daelkyr are the source of almost all aberrations in Eberron. They created illythids by mutating Gish they kidnapped from the astral plane, dolgrims, dolgaunts and dolgarr by mutating captured goblinoids, chokers by mutating captured halflings, neogi and derro by mutating captured dwarfs, and beholders, gibbering beasts and slimes from the sludge that was left in the fleshcrafting cauldrons. Some even say they also created basilisks and medusae - a theory medusae themselves object to vehemently. About the only major aberrations they didn't create are Aboleths who, as always, predate everything. Using their vast and ever growing armies of fleshcrafted horrors the daelkyr waged a war against everyone on Khorvaire, but mostly the Dhakaani empire, who were the most organized and powerful force on the continent. Dhakaani goblinoids fought the daelkyr threat for thousands of years, slowly losing ground and sanity, and it's rumored daelkyr broke the eusocial bond between goblinoids to weaken them. Still, Dhakaani managed to kill a lot of daelkyr until only six of them remained. Unfortunately those six were the trickiest ones with multiple contingencies and proved to be either unkillable or capable of resurrecting themselves. With their empire crumbling around them it looked like Dhakaani would eventually lose, until suddenly some orc druids from the ass end of nowhere started teleporting around and binding the remaining daelkyr to prison demiplanes in Khyber, saving Khorvaire and probably the entirety of Eberron.

In the current days all six daelkyr remain bound to their prison demiplanes, but are not sleeping like similarly bound Overlords and actively scheme to achieve... something. No one sure what, because the actions of daelkyr agents don't follow any sane agenda. Daelkyr are one of the two go-to patrons for insane evil cultists known collectively as "cults of dragon below". Unlike the Overlords they are still active threats as while they are incapable of leaving their prison demiplanes, their armies are free to go in and out. Several wars are currently fought against said armies, most notably below the Mror Holds, where dwarves try to reclaim their ancestral empire, below the Towering Woods, where druids try to contain the biggest portal to Dyrrn's prison, and under Xendrik where Umbragen Drow fight for their survival. Another major hot-spot is the Shadow Marches, the aforementioned ass end of nowhere from where the orc druids that saved the world came from. Those druids called Gatekeepers are still busy keeping daelkyr locked as almost half the orc tribes in the marches are worshiping the Lords of Madness and want to set them free, keeping Shadow Marches in a constant tribal war.

Known Daelkyr

• Dyrrn, the Corruptor: the grand daddy daelkyr, the patron saint of Getting Shit Done and arguably the mightiest of its kind (or at least of those who invaded Khorvaire). All those humanoids corrupted and turned into aberrations? It's their doing. The plague of Silence that broke the Dhakaani empire? Theirs too. All three major current wars against daelkyr? All against Dyrrn's armies. Most other daelkyr see themselves as artists or scientists, but Dyrrn is the conqueror. Mind Flayers and Dol worship it as their divine creator and call it the Overmind. Yes, Illithids WORSHIP the guy. It's also credited with creating the Clone spell. Goblins are certain they killed it during the war. Which they might be right about, but considering this is the guy who invented cloning spare bodies for your soul to shunt into in case you die...

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• Belashyrra, the Lord of Eyes: the daelkyr obsessed with secrets and visions. It created beholders and beholderkin, although there's no love lost between them and their creator with most of them fucking off and doing their own thing when Belashyrra got locked in its prison demiplane. Belashyrra is one of the most popular patrons among the cults of Dragon Below, granting them powers of vision and eye ray magic in exchange of their sanity.

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• Kyrzin, the Prince of Slime: the guy responsible for creating all the slimes and gibbering beasts. Orc cultists of Shadow Marches mostly worship this guy and it grants their followers powers over disease and poison, both to inflict it and cure it.
• Orlassk, the Lord of Stone: the guy credited with creating all the monsters that can turn flesh to stone. You probably should not mention that to any Medusa as they consider this theory heretical. Its cults are rare and are mostly Wizards of Transmutation as it grants their followers increased understanding of transmutation magic. It managed to bind their prison to a giant gargoyle and is generally content with traveling and messing with people in deep Khyber, not interested much in the world above.
• Valaara, the Crawling Queen: the daelkyr responsible for creating most of the monstrous insectoids and insectoid symbionts. Canon materials haven't said much more about it, but Keith Baker's *Exploring Eberron*, which most fans pretty much take as canon, does go a bit more in-depth. Her minions unsurprisingly mostly consist of buglike creatures, and her humanoid worshipers often fall under the delusion that they are insects transformed into or trapped in a humanoid body or that they are being controlled by parasites.
• Avassh, the Twister of Roots: the daelkyr credited with creating monstrous plants. Again, not much above that.