Koz (also spelled Hakos or Koz) is mentioned in the Bible as a person linked to priestly families after the exile. His descendants were among those who could not prove their priestly lineage when the Israelites returned from Babylon. The name also appears in 1 Chronicles as a descendant of Judah.
The descendants of Koz (the sons of Hakos) were among the priestly families that returned from exile in Babylon but had difficulty proving their priestly ancestry.
61And among the sons of the priests: the sons of Habaiah, the sons of Hakkoz, and the sons of Barzillai, who had married one of the daughters of Barzillai the Gileadite and was called by their name.
4Next to them Meremoth son of Uriah, son of Hakkoz, made repairs. Next to them Meshullam son of Berechiah, son of Meshezabel, made repairs, and next to them Zadok son of Baana.
63And among the priests: the descendants of Hobaiah, Hakkoz, and Barzillai — the one who had married a daughter of Barzillai the Gileadite and took his family name.
65The governor ordered them not to eat any of the most holy food until a priest should arise to consult the Urim and Thummim.[^1]
[^1]: Urim and Thummim: sacred objects kept by the high priest and used to seek God's decision.