Blachernitissa (Greek: Βλαχερνίτισσα), also called Theotokos of Blachernae (Θεοτόκος των Βλαχερνών, Θεοτόκος η Βλαχερνίτισσα) or Our Lady of Blachernae (Παναγία η Βλαχερνίτισσα), is a 7th-century encaustic icon representing the Most Holy Theotokos and Ever-Virgin Mary. It is also the name given to the Church built in honour of the Virgin Mary in the Blachernae section of Constantinople. The name Blachernae possibly derived from the name of a Vlach (sometimes written as Blach or Blasi), who came to Constantinople from the lower Danube
The Theotokos was considered to be the intercessory protectress par excellence of Constantinople and, indeed, of the entire Eastern Roman Empire (called "Byzantium" by some modern Western scholars). Blachernitissa is unusual among Orthodox icons in that it is not flat, but is formed in bas relief. According to Sacred Tradition, the icon Blachernitissa was made of wax combined with the ashes of Christian martyrs who had been killed in the 6th century. The Church of St. Mary of Blachernae (which hosted the icon) was sited close to the Blachernae imperial palace.
The Theotokos' intercession, asked through veneration and prayer before the icon, was credited with saving Constantinople from the Persians during the reign of Heraclius and later from the Arabs. These miracles are commemorated annually in the Orthodox Church on the Saturday of the Akathist on the Fifth Saturday of Great Lent.