Onias the High Priest of 2 and 4 Maccabees (Ὀνίας, Onias). Often referred to as Onias III. High priest until the reign of Antiochus IV Epiphanes, at which time his brother Jason “obtained the high priesthood by corruption” (2 Maccabees 3:1; 4:7); son of Simon II (Josephus, Antiquities 12.225) and father of Onias of Heliopolis.

Onias initially proved to be a successful high priest (2 Maccabees 3:1–3). The first major documented event in his tenure is his conflict with Simon (of the tribe of Benjamin). Due to his failure to win a dispute concerning the administration of the city market, Simon went to Apollonius, the general of the Syrian army, and claimed that there were riches within the Jewish temple that potentially could be taken as tribute. Apollonius either went himself (4 Maccabees 4:1–14) or sent an emissary named Heliodorus (2 Maccabees 3:1–28) to acquire the sum of money in the temple. Both accounts describe a miracle in which a heavenly apparition prevents any wealth being taken.

When Antiochus IV Epiphanes ascended to the Seleucid throne, Onias was removed from the priesthood (2 Maccabees 4:7–8) and eventually murdered (2 Maccabees 4:30–35).