deacon of Alexandria who became bishop of Laodicea, after risking his life by serving Christian martyrs during the persecutions of the Roman emperors Decius (250) and Valerian (257). He was a former pupil of the illustrious theologian Origen.

When Alexandria was besieged in 262 by troops of Valerian's successor and son, Gallienus, Eusebius and his friend Anatolius negotiated the release of persecuted Christians and noncombatants who had been trapped by imperial soldiers and whom Eusebius later tended. In 264 Bishop Dionysius of Alexandria sent Eusebius as emissary to a synod at Antioch, whose bishop, Paul, was being tried for heresy. On his return journey, Eusebius, by then revered for his saintliness, was persuaded to become bishop of Laodicea. After his death, he was succeeded by Anatolius.