Paraskeva of the Balkans, alternatively known as Petka, was an ascetic female saint of the 11th century. She was born in Epivates, near present-day Istanbul, and, according to legends, had visions of the Virgin Mary. After living in Chalcedon and Heraclea Pontica, she settled in a convent in the desert near the Jordan River. An angel told her to return to her homeland, and two years later she died at the age of 27. Veneration of Saint Paraskeva began to spread in the 14th century from Bulgaria into the Danubian Principalities of Wallachia and Moldavia. There was confusion over her identity and attributes because her Greek name Παρασκευή "Paraskeuḗ, Paraskevi" means "Friday," and translations in other languages, such as Romanian and Serbian, were "Saint Friday". Her life continues to be celebrated in many Orthodox countries, and her feast day is commemorated on October 14 in the Eastern Orthodox Church.

Paraskeva was born in the town of Epivates (today's Selimpaşa, close to Istanbul) on the shore of the Sea of Marmara. Her parents were wealthy landowners.

Legend says that as a child, Paraskeva heard in a church the Lord's words: "Whoever wants to come after Me, let him deny himself, and take up his cross, and follow Me." (Mark 8, 34). These words would determine her to give her rich clothes away to the poor and to flee to Constantinople. Her parents, who did not support her decision to follow an ascetic, religious life, looked for her in various cities. Paraskeva fled to Chalcedon in Asia Minor, and afterwards lived at the church of the Most Holy Theotokos in Heraclea Pontica in Bithynia. She led an austere life, experiencing visions of the Virgin Mary. Her travels took her to Jerusalem; she wished to spend the rest of her life there. After seeing Jerusalem, she settled in a convent in the desert near the Jordan River.

When she was 25, an angel appeared, telling her to return to her homeland. She returned to Constantinople and then settled down a short distance west, living the last two years of her life in the village of Kallikrateia, in the church of the Holy Apostles, where she died age 27. The former village is now a neighbourhood in Eastern Thrace called Mimarsinan.

According to Christian tradition, many years after Paraskeva's death, an old sinner was buried near her long-forgotten grave in Kallikrateia, after which Paraskeva appeared in a dream to a local monk and complained about the impure neighbor. The vision informed the monk where she had been buried; when the body was unearthed, it was found to be incorrupt. The relics were translated to the church of the Holy Apostles in Kallikrateia.

In subsequent years, Paraskeva's relics were transferred to various churches in the region.

In 1238, the relics were transferred from Kallikrateia to Veliko Tarnovo, capital of the Second Bulgarian Empire. In Bulgaria she is venerated as Sveta Petka Tarnovska, "of Tarnovo".

In 1393, they were transferred to Belgrade, specifically the Ružica Church.