Who is the sister of Anubis?

When the father of Anubis is Ra; his sister can be Ashart, Anat, Bast, Wadjet, Anhur, Ma'at, Nekhbet, Serqet, Hathor and Mut.

If his father is Osiris - or his mother is Isis, his sister can be Bast. This is due because Greek rulers of Egypt after Alexander the Great saw Bast as being Artemis, and thus her brother was Horus (Apollo). Anubis is sometimes seen as a brother of Horus when his father is Osiris or his mother is Isis.