This list of mythical creatures that begin with this letter and I am constantly gathering information from each continent, and is continually being updated.
Night Hag (Worldwide)
The night hag or old hag is the name given to a supernatural creature, commonly associated with the phenomenon of sleep paralysis. It is a phenomenon which a person feels during a presence of a supernatural malevolent being which immobilizes the person as if sitting on their chest or the foot of their bed. The word "night-mare" or "nightmare" was used to describe this phenomenon before the word received its modern, more general meaning.
Night hags were horrendously hideous beings, unrivaled in their repulsiveness even when compared to most other hags and much more so when compared to ordinary crones. To describe them as merely ugly was an immeasurable understatement and comparing them to human women at all could be seen as an affront to the gender.