Morrígan

Morrígan is one of the old gods of Winter and Death.

Appearance
The Winter Goddess is a tall woman with exceptionally long, dark and wavy hair with a motherly figure and a pregnant belly. Her eyes are bright with white pupils. She's clad in a long dress that reaches down to her feet, it's black from the ankles and upwards while the lower parts are white.

Personality
The mother comes off as a stoic and serious being while being presented in a regal presence, yet her demeanor changes somewhat when she takes notice of a branch from an oak mistletoe. As she takes ahold of it, her mood becomes much happier.

The Winter Goddess clearly appreciates gifts.

History
The Winter Goddess is first mentioned just before the night of Yule, an important cycle of the year that showcases the shift between the winter and the coming spring, by the Heralds of Yule and later by Elias.

Yule Arc
The Winter Goddess later seen riding on top of another god, it's revealed that she's pregnant as she unknowingly passes by Elias, Chise and Ruth. Before leaving she takes notice and picks up a mistletoe.

Skills and Abilities
As an old god, the full extent of the Winter Goddess's powers are unknown but she's known to hold power over the world of winter. Being called a god of both winter and death, it's suspected that she holds some sort of powers related to both of these realms and humans have celebrated and made offerings for her coming during the night of Yule, even since the times of old. As such, she's feared by even individuals such as Elias.

The Deer
Whether their relationship is that of friends or that of servant and mistress is unknown. They're both referred to as gods and while they haven't been seen exchanging words with one another, their presence together and the fact that she's riding him towards their destination suggests that they're on good terms and that they hold some level of trust for one another.

Trivia

 * The concept of the Winter Goddess is a slight alteration of the Goddess of Yule, a being that becomes the Great Mother before giving birth to the new Sun Goddess.