Saint Parthenios, Bishop of Radovisdiou, was an eighteenth-century Greek hierarch who served in the mountainous interior of Epirus and Thessaly during the period of Ottoman rule. By tradition he was born in the early eighteenth century in the village of Vatsounia in the Agrafa region (given in some accounts as Vatsounia of Karditsa), the child of pious Orthodox farmers. He entered monastic life at a young age, was at first assigned to the care of the monastery's animals, and was later ordained to the priesthood before his elevation to the episcopate.
As Bishop of Radovisdiou — a diocese centered on the district of Radovizi that extended into parts of the present-day region of Arta — he ministered amid the hardships of Ottoman occupation. His episcopal seat lay first at Vrangiana in Evrytania and was afterward moved to Velentziko. The synaxarion records that he kept a strict ascetic discipline while tending to both the spiritual and material needs of his people, and it preserves accounts of secret acts of charity performed by night, such as clearing stones from a poor man's field over many nights by moonlight.
Saint Parthenios reposed on July 21, 1777, at Velentziko and was buried behind the altar of the local Church of the Holy Unmercenaries. When his grave was opened on July 21, 1810, thirty-five years after his death, his remains were found to give off a sweet fragrance, a sign by which the Church recognizes sanctity. He is commemorated on July 21 and is counted among the saints especially honored in Arta. A liturgical service in his honor was composed by the monk Gerasimos Mikragiannanitis and published in 1971.