Justin, Iustinus, or Iousinos (Ἰουστῖνος) was a Byzantine and Eastern Roman emperor of the 5th and 6th centuries. He is the founder of the Justinian Dynasty and his nephew, Justinian, would succeed him and outshine his legacy. He ended the Acacian schism by professing his Orthodoxy, unlike his predecessors who frequently had monophysite tendencies. Justin famously called upon Kaleb of Axum to invade Himyar for the sake of the Christians who were being persecuted there. His reign was also marked by interactions between the Sassanids and Byzantines.