Helladius may refer to: * Alexander Helladius (1686–?), Greek scholar and humanist * Helladius (4th century hieromartyr) * Helladius of Kiev, Ukrainian monk and saint * Helladius of Auxerre (died 387), Christian bishop and saint * Helladius of Caesarea, Christian bishop, named by an edict of Theodosius I (30 July 381) to an episcopal see * Helladius (grammarian), grammarian, professor, and a priest of Zeus * Helladius of Ptolemais, Christian bishop, present at the First Council of Ephesus (431) * Helladius of Tarsus, Christian bishop, condemned at the First Council of Ephesus (431) * Helladius of Toledo (died 633), Christian bishop and saint * Helladius and Theophilus, two Christian martyrs in Libya, feast day 8 January * Helladius, Crescentius, Paul and Dioscorides, Christian m