Lucius Septimius Archelaus

Lucius Septimius Archelaus was an imperial freedman and a prominent member of a Mithraic community associated with the imperial household in Rome. His funerary inscription identifies him as Augustorum trium libertus, a freedman of the three Augusti Septimius Severus, Caracalla and Geta, and as Pater et sacerdos Invicti Mithrae domus Augustanae, Father and priest of Invincible Mithras of the imperial household (TNMM 453).

The reference to the three emperors dates his manumission, and probably the inscription, to their brief period of joint rule between 209 and 211, although the monument may have been erected somewhat later. Archelaus commissioned the plaque during his lifetime for himself, his freeborn wife Cosia Primitiva, whom he describes as deserving, and for their freedmen, freedwomen and descendants.

His title provides important evidence for Mithraic worship within the domus Augustana. Jaime Alvar (2008) interprets it as an indication that one or more Mithraea served the imperial household on the Palatine. Aleš Chalupa (2023) likewise regards the existence of such a sanctuary as probable, most likely serving slaves, freedmen and members of the imperial administration, although no Mithraeum has yet been securely identified archaeologically. The inscription does not, however, demonstrate the personal involvement of the emperors or the existence of an official imperial cult of Mithras.