In Egyptian mythology, Nephthys (Nebt-het) is the name of the sister and wife of Seth, and sister of Isis and Osiris. She also is the mother (variantly by Set or by Osiris) of Anubis. She abandoned Seth when he killed Osiris, and assisted Isis in the care of Horus and the resurrection of Osiris. She was, along with her sister, considered the special protectress of the dead, and she was the guardian of Hapi, the protector of the lungs of the deceased.
SEE ALSO Hapi, Horus, Isis, Osiris, Seth.
[Source: Shawn C. Knight, "Egyptian Mythology FAQ" ]