The altar-priest performed duties related to the preparation of the initiation but not to the initiation itself. The office rarely appears in ancient inscriptions, and its responsibilities are unclear. It seems possible that the altar-priest was responsible for sacrificing animals or, in general, for sacrifices to the gods. He came from the genos of the Kerykes. He was aeisitos for life and had the right to erect a statue in the sanctuary in Eleusis.

Archaic ram's head, imitation of a gutter-spout, from corner of the sima of the Peisistratan Telesterion, sculpture, American School of Classical Studies / Alison Frantz Photographic Collection © American School of Classical Studies at Athens, Archives, Alison Frantz Photographic Collection

In Roman times the office gained more prestige. It attracted upper-class individuals such as Leucius Memmius, who claimed to have prepared for initiation three emperors: Lucius Verus, Marcus Aurelius, and Commodus. As mystagogos, the altar-priest was entitled to receive half an obol from each candidate for initiation. At some point in the evolution of the Mysteries (and certainly after the classical period), the altar-priest participated in the sacred performance impersonating Selene.

Initiation hall of the mysteries, long frequented by the devout (N.N.W.). Eleusis, 1907, photograph, Boston Public Library © Boston Public Library