She was depicted as a woman with the hieroglyphs of her name (a basket and a house on top of each other) on her head, though she was also sometimes given wings or the form of a bird (the kite), making her a solar deity, as well as a deity of the dead. In the later period, she became the mother of Anubis (the god of the dead) through Osiris.

As comforter, she stood at the birth-bed to offer comfort and help with the birth of new born children - Isis was seen as the midwife. The two sisters were often together, only being able to be told apart by the hieroglyph on their heads. Also, like her sister, she was thought to have great magical powers - she was the Mighty One of Words of Power.

Yet, originally, where Isis was visible, birth, growth, development and vigour, Nephthys was invisible, death, decay, diminution and immobility. She was the darkness to Isis' light. Isis was the day, her twin sister the night.

The goddesses were personified by two priestesses who were virgins and who were ceremonially pure; the hair of their limbs was to be shaved off, they were to wear ram's wool garlands upon their heads, and to hold tambourines in their hands; on the arm of one of them was to be a fillet inscribed "To Isis," and on the arm of the other was to be a fillet inscribed "To Nephthys." On five days during the month of December these women took their places in the temple of Abydos and, assisted by the Kher Heb, or precentor, they sang a series of groups of verses to the god.

Hail, thou lord of the underworld, thou Bull of those who are therein, thou Image of Ra-Harmachis, thou Babe of beautiful appearance, come thou to us in peace. Thou didst repel thy disasters, thou didst drive away evil hap; Lord, come to us in peace.

O Un-nefer, lord of food, thou chief, thou who art of terrible majesty, thou God, president of the gods, when thou dost inundate the land [all] things are engendered. Thou art gentler than the gods. The emanation of thy body make the dead and the living to live, O thou lord of food, thou prince of green herbs, thou mighty lord, thou staff of life, thou giver of offerings to the gods, and of sepulchral meals to the blessed dead. Thy soul flieth after Ra, thou shinest at dawn, thou settest at twilight, thou riseth every day; thou shalt rise on the left hand of Atmu for ever and ever. Thou art the glorious one, the vicar of Ra; the company of the gods cometh to thee invoking thy face, the flame whereof reacheth unto thine enemies. We rejoice when thou gatherest together thy bones, and when thou hast made whole thy body daily. Anubis cometh to thee, and the two sisters (i.e., Isis and Nephthys) come to thee. They have obtained beautiful things for thee, and they gather together thy limbs for thee, and they seek to put together the mutilated members of thy body. Wipe thou the impurities which are on them upon our hair and come thou to us having no recollection of that which hath caused thee sorrow.

Come thou in thy attribute of "Prince of the Earth," lay aside thy trepidation and be at peace with us, O Lord. Thou shalt be proclaimed heir of the world, and the One god, and the fulfiller of the designs of the gods. All the gods invoke thee, come therefore to thy temple and be not afraid. O Ra (i.e., Osiris), thou art beloved of Isis and Nephthys; rest thou in thy habitation for ever.

• Lady of the Body (of the Gods)
• Dweller within Senu
• Lady of Heaven
• Mistress of the Gods
• Great Goddess, Lady of Life