Hosius of Corduba (c. 256–359), also known as Osius or Ossius, was a bishop of Corduba (now Córdoba, Spain) and an important and prominent advocate for Homoousion Christianity in the Arian controversy that divided the early Christianity. He probably presided at the First Council of Nicaea and also presided at the Council of Serdica. After Lactantius, he was the closest Christian advisor to Emperor Constantine the Great and guided the content of public utterances, such as Constantine's Oration to the Saints, addressed to the assembled bishops.