Adamantius (Ancient Greek: Ἀδαμάντιος; fl.
474–479) was a politician of the Eastern Roman Empire, praefectus urbi of Constantinople (474–479), patricius and honorary consul.
Between 474 and 479, Adamantius held the office of praefectus urbi of Constantinople.
That year he was conferred consular honours by Emperor Zeno and sent as envoy to the rebel general Theodoric the Great.
He went to Thessalonica, where he freed the ex-consul Iohannes from an enraged mob, and joined with Sabinianus Magnus at Edessa; they reached Theodoric in Dyrrachium, where they started negotiations, but Zeno recalled them back when the rebels kept on attacking imperial territories.