Léon VI le Sage
The Byzantine diocese of Chalkis was initially a suffragan of the Archdiocese of Corinth, but in the 9th century was transferred to the Metropolitan of Athens, remaining in the sway of the Patriarchate of Constantinople. It was also known as Euripo, like it's mentioned in the Byzantine imperial Notitia Episcopatuum since emperor Leo VI the Wise (886-912).