Night Hag

The Night Hags of Eberron are enigmatic and mysterious native fiends. Along with the Rakshasa, they were the first children of Khyber, but they seem to have no sympathy or love for the Rakshasa or the Overlords.
Night Hags originated in Khyber, in a demiplane called the First Night. Thirteen night hags emerged from the first night, old on their first day, called grandmothers before there were even children, or mothers. Twelve of these hags formed covens of three, with the exception of Sora Kell, who even then walked her own path. Whilst most fiends are tied to one of the overlords, this doesn't seem to be the case with the Night Hags, as there is no overlord within the First Night. According to records in the vaults of the Kech Volaar, Jhazaal Dhakaan theorised that the Night Hags embodied the curiosity of Khyber herself, and that whilst they were still more than willing to lead mortals to despair and misery, they lacked the sheer supernatural malevolence of the overlords, and have no desire to rule over Eberron.
Instead, the Night Hags love to watch the stories of the world unfold, especially those that end in tragedy. During the Age of Demons, the Night Hags were a neutral party which acted as intermediaries between the powers of the age, the mortals, the fiends, the dragons. The hags took no sides in the first wars, just content to watch them play out and see where the pieces landed. The hags loved being in the middle of the all the chaos, and in watching history being made.
Night hags wield a measure of power within Dal Quor, and can manipulate dreams. Over the millennia, they have come to an understanding with the Quori, and Dal Quor is a very large place. The hags are able to smell the touch of a quori on a dream, and both the hags and the quori will do their best to stay out of each other's way. Similarly, the hags generally avoid points of interest within Dal Quor, such as the Uul Dhakaan, unless they have a specific reason for interfering.
There are many stories of night hags throughout the world, many of which were collected by Dorius Alyre Korran, and the scholar had some issues reconciling the seemingly vast spectrum of power the hags seemed to possess. There are stories of Sora Kell shattering entire armies single handedly, but there are equally tales of night hags being bested by single champions. Even more concerning, when Dorius catalogued the stories they uncovered, there are more than thirteen hags mentioned.
The answer seems to come from another record from ancient Dhakaan. According to Dhakaani legend, a party of Dhakaani champions led by the dirge singer Uula Korkala quested to eliminate the primal night hag Sora Ghazra, whom they believed to be the source of a disaster that had befallen the empire. Wielding artifacts of the empire, this group was able to defeat the hag, but it is no small task to kill an immortal being. As she fell, Ghazra's essence infected those that had slain her, and they were plagued with nightmares for days. Unable to sleep, the party wasted away until eventually they were reshaped into hags, lesser versions of the being they had destroyed. Those new night hags, of the line of Sora Ghazra, also carried this curse, and anybody who killed one of those hags would be doomed to themselves become a hag.