Archmagos — a senior priest of the Cult Mechanicus, above the rank of Magos. The title is rarely held without a qualifier:
- Archmagos Dominus — supreme authority over a forge-line or expedition; commanding rank.
- Archmagos Veneratus — exceptionally aged or honoured Archmagos, often retired from active operations into archival or doctrinal oversight.
- Archmagos Explorator — leader of a recovery expedition.
- Archmagos Reductor, Archmagos Cybernetica, etc. — heads of an order’s regional cell.
Promotion to Archmagos is by acclamation of peers — a vote among the senior priests of a forge-world’s Synod, ratified or vetoed by the Fabricator-General. There is no fixed number of Archmagi. There are roughly — though no canonical count exists — between several thousand and tens of thousands across the Imperium at any given time.