Morax is a Goddess of demons, and more powerful than the demon lords (the most notable of whom are Deceit, Decay, and Desolation). She is very mysterious and not much is known about her. There is debate on whether or not she is located in the mortal realm or any of the planar worlds.
Although the demons claim her natural form is demonic, she changes her appearance to reflect the race of those she meets. Humans claim she looks human, elves claim she looks elven, and dwarves claim she looks dwarven. Respected sages, archwizards, and alchemists, who have studied these finding, believe her appearance is just a projected illusion. They claim she never leaves the space from which she resides, and instead uses each races's culture and expectations to construct an image of herself that would be accepted by each race.
Of course those who side with evil worship Morax, but even those who would not necessarily align themselves with evil occasionally pray to her as well. Those who wish for selfish things, such as power or wealth will turn to her. Morax will only grant wishes to those who sacrifice to her. The sacrifices can vary depending upon the wish, but it must always be something that is precious to the sacrificer.
Some people would go to the extreme to gain her favour, sacrificing the lives of their parents or children—but even a grand sacrifice such as that does not guarantee her favour. Morax chooses who she will help based on a whim.