Rajani

The Mother of Demons. When the Elder Gods, her siblings of a sort, were created, they were massive positive energy, and to offset such, there was a large amount of negative energy as a result. The creator shaped this energy into Rajani. The negative to their positive. While the created life and other such things, she created demons, and the initial demon plane. Since then, the demons have evolved and many varieties and planes of existence formed. She has always wanted to influence the mortal realm, but she was never quite able to. Her demonic spawn however managed to at various points in history. So her influence did spread over, and still lingers in many ways. She's able to shapeshift and walk among any of the planes, with her power not being as great in the mortal realm as part of a deal with the other elder gods. She's still more or less a goddess in this realm, and cannot be harmed by most anything. As the demons evolved over millions of years, plenty of the planes do not worship her or even really think about her. Many know her still, but she doesn't mind, she has her loyal subjects. She can still walk at her full power in these realms.

As she was around before the creation of time itself, she's truly ageless like The Creator and other Elder Gods.

She is capable of shifting her form, and like the others of her level of power, she wasn't really created with any gender or sex in mind, she has taken after the female form later in her life. The horned anthro form is her common form. But art from all sorts of cultures and realms depict her wildly different. From a mere fish to a horrific, demonic mass of flesh and tendrils in some incomprehensible mess of a being. Imagination is truly the limit of her power. Of course, she knows subtlety and will read the room before shifting. These days she's simply an admirer.

Her love of jewels and clothing she's often seen in comes from many sources of mortal and demon kind. While most gods would adore their followers take after them, she doesn't mind taking after them in some ways.