High Priest after the Order of Melchizedek
כֹּהֵן גָּדוֹל
The great High Priest — not of Aaron's line but of Melchizedek's deathless order, sworn in Psalm 110.
King and priest were separated offices in Israel — Uzziah was struck for crossing the line. Psalm 110 swears both onto one figure by an older order, and Hebrews builds its whole argument there. Jewish tradition also wrestled richly with Melchizedek; Qumran expected him as a heavenly redeemer.
First occurrence
Ps 110:4 — 'You are a priest forever after the order of Malki-Tzedek'
Key passages
Gen 14:18 — Melchizedek: king of Salem, priest of El Elyon, bread and wine
Heb 4:14 — 'A great High Priest who has passed through the heavens'
Heb 7:25 — 'He always lives to make intercession'
Zech 6:13 — 'A priest on His throne' — the offices joined
In the Greek Scriptures
Ἀρχιερεύς