Theodora of Thessaloniki was a 9th-century Byzantine nun born in Aegina. After losing her brother to Arab raids, she moved to Thessaloniki, where she eventually entered the convent of St. Stephen the Protomartyr following her husband's death in 837. She was recognized for her humility, hard work, and obedience within the monastic community. Her life is documented in an extensive hagiography, which remains the longest biographical account of a holy woman from the Byzantine era.