Theosebia was a 4th-century Christian leader from Anatolia, recognized as a deaconess or potentially a presbyter. While specific details regarding her birth remain unknown, she was a prominent figure in the church at Nyssa. Historical accounts, including a letter from Gregory Nazianzen, suggest she held a significant role alongside Gregory of Nyssa. Because of her close connection to the Cappadocian circle, scholars debate whether she was a sister or the wife of Gregory of Nyssa, though she is celebrated for her spiritual distinction and leadership.