Nephthys

As the wife of Set, Nephthys herself had many dark qualities. She was the Goddess of the darkness, mystery, secrets, magick and dreams. Nephthys was the dark sister of Isis. She is sometimes thought of as a Goddess of the Dead but she really didn't fulfill any roles in that respect, other than her relation to Anubis.

She had no children by Set, but she did trick Osiris into impregnating her. The result was Anubis, God of the Dead. This could be the root of Set's unending jealousy of Osiris.