Who was Set's wife and Osiris's sister?

The story behind the answer

Nephthys is correct: she is both the sister of Osiris and Isis and the traditional consort of Set. As a daughter of Geb (Earth) and Nut (Sky), Nephthys belongs to the core divine family. Though married to Set, she sides with Isis to mourn and protect Osiris, highlighting her role as a goddess of mourning and funerary rites.

Nephthys and Isis often appear as protective “sister goddesses” at the head and foot of coffins, safeguarding the dead; in some myths, Nephthys is also the mother of Anubis. Memory tip: pair the vowels—Isis with Osiris—leaving the consonants—Set with Nephthys (N-Set)—to remember who’s partnered with whom.