Nephthys was an ancient goddess, who was referenced in texts dating back to the Old Kingdom. She was a member of the Ennead of Heliopolis as the daughter of Geb and Nut and the sister of Osiris, Isis and Horus and the sister and wife of Set. When the Ennead and Ogdoad merged, Nephthys was given a place on Ra’s boat so that she could accompany him on his journey through the underworld.
Nephthys is the Greek pronunciation of her name. To the Ancient Egyptians she was Nebthwt (Nebhhwt or Nebthet) meaning “the Mistress of the House”. The word “hwt” (“house”) may refer to the sky (as in Hwt-hor, the “House of Horus” – the name of Hathor), but it also refers to either the royal family or Egypt as a whole. The latter makes a great deal of sense as she was described as the head of the household of the gods and was thought to extend her protection to the head female of every household. She was sometimes associated with Ptah-Tanen in representing Lower Egypt, while Khnum and Isis represented Upper Egypt.
It seems that she was originally conceived of as the female counterpart of Set. He represented the desert, while she represented the air. Set was infertile (like the desert that he represented) and was frequently described as either bisexual or gay and so Nephthys was often considered to be barren. As a goddess of the air, she could take the form of a bird, and because she was barren she was associated with the vulture – a bird which the Egyptians believed did not bear children. The Egyptians thought that all vultures were female (because there is very little difference in the appearance of a male vulture), and that they were spontaneously created from the air. While the care shown by a mother vulture for her child was highly respected, the Egyptians also recognised that vultures fed on carrion and associated them with death and decay.
As a result, Nephthys became a goddess of death and mourning.
Professional mourners were known as the “Hawks of Nephthys”, in recognition of her role as a goddess of mourning. It was also believed that she protected Hapi in his role as of the Four sons of Horus (who guarded the organs stored in the four canopic jars). Hapi protected the lungs, and as a goddes of the air Nephthys was his guardian. She was also one of the four goddesses who guarded the shrine buried with the Pharaoh. She appears with Isis, Selkit (Serqet) and Neith on the gilded shrine of Tutankhamun, but was often depicted with Isis, Bast and Hathor in this role. Yet, she was also said to be the source of both rain and the Nile river (associating her with Anuket) and was thought to protect women in childbirth (with the assistance of her sister, Isis). Thus she was closely associated with both death and life.