August 18 in Eastern Orthodox liturgical calendars is a feast day and a day of commemoration of saints and martyrs. Although some Orthodox churches use the Revised Julian Calendar and others use the traditional Julian calendar, the fixed commemorations for their respective August 18 are broadly the same, no matter which calendar is used.
Martyrs Florus and Laurus of Illyria, twin brothers who worked as stonemasons (2nd century)
The Holy Host of Paupers (300 martyrs), brought together by Saints Florus and Laurus, who smashed the statues of the pagan gods and were martyred by fire.
Martyrs Hermes, Serapion, Polyaenus of Rome (2nd century)
Hieromartyr Emilian, Bishop of Trebia in Umbria, and lay martyrs Hilarion, Dionysius, Hermippus, and about 1,000 others, in Italy (c. 300)
Venerable Barnabas and his nephew Sophronius, founders of Mount Mela Monastery (Panagia Soumela), near Trebizond (412)
Venerable Christopher of Trebizond, Abbot of Mount Mela Monastery (Panagia Soumela) (668)
Saints John (674) and George (683), Patriarchs of Constantinople.
Martyr Juliana near Strobilos in Lycia.
Martyr Leo, drowned off the coast of Myra in Lycia.
The 4 Venerable Ascetics, reposed in peace.
Saint Macarius, Abbot of the Pelekete Monastery near Prusa, Bithynia (840) (see also: April 1)
Venerable John of Rila, founder and Abbot of Rila Monastery, Bulgaria (946) (see also: October 19)
Saint Agapitus of Palestrina, a fifteen-year-old who bravely confessed Christ and was martyred in Palestrina near Rome (c. 274)
Martyrs John and Crispus, priests in Rome who devoted themselves to recovering and burying the bodies of the martyrs, for which they also suffered martyrdom.
Saint Firminus of Metz, Greek or Italian by origin, he was Bishop of Metz in France for eight years, Confessor (496)
Saint Daig Maccairill (Daig, Dagaeus, Daganus), disciple of St Finian, he founded a monastery at Inis Cain Dega (Inniskeen), and was both abbot and bishop (586)
Saint Milo, a monk together with his father at Fontenelle Abbey in France, and later a hermit (c. 740)