It Started With a Kidnapped Pig...
Shar, the Mistress of the Night, was the goddess of darkness and the caverns of Faerûn. Counterpart to her twin Selûne, she presided over caverns, darkness, dungeons, forgetfulness, loss, night, secrets, and the Underdark. Among her array of twisted powers was the ability to see everything that lay or happened in the dark. Shar’s symbol was a black disk with a deep purple border. Shar was also the creator of the Shadow Weave, which was a counterpart and attack upon the Weave, controlled by Mystra and her successors, before both of the Weaves fell into ruin during the Spellplague.
Shar created the Shadowfell, a gloomy plane of shadow and depression where she rules.
Relationships with other gods
Shar and her sister Selûne coalesced out of the material of Realmspace after it was created by Ao. They were incredibly close at first, so much so that they believed themselves to be the same being. They worked together to create the heavens and the planets and then created Chauntea to embody the planets and infuse them with life. Selûne lit the worlds while Shar coated them in shadows. They quarrelled violently about the worlds they created and have been enemies ever since.
Shar has spent considerable energy trying to wrest control of the Weave away from Mystra, and counts her as an enemy. Shar made allies of Bane and a patsy of Cyric in 1374 DR and organised for Cyric to kill Mystra and take the blame for it, although Mystra was reborn a century later.