Arimanius (Greek: Αρειμάνιος Areimánios; Latin: Arīmanius) is a name for an obscure deity found in a few Greek literary texts and five Latin inscriptions. It is supposed to be the opponent of Oromazes (Ancient Greek: Ὡρομάζης Hōromázēs), the god of light. In classic texts, in the context of Zoroastrianism, Areimanios (with variations) fairly clearly refers to the Greeks' and Romans' interpretation of the Persian Ahriman.[1]: 2034 The Latin inscriptions which were found in a Mithraic context suggest a re-defined or different deity with a near-identical name.[2]: 226
The most extended passage in classical literature on Areimanios is in two sections of Plutarch[3] who describes him as the dark or evil side in a dualistic opposition with Oromazes (for Ohrmuzd or Ahura Mazda).[5] However, Plutarch[3] was specifically describing Persian Zoroastrianism, rather than the obscure Arimanius of the Mysteries of Mithras. In the context of Roman Mithraism, from the way the name is used, it seems implausible that it refers to an evil entity, no matter how formidable his depictions might appear.[2]: 226–227